Transplant before or after topping?

Seeing as how this is your first grow, lets try not to make things too complicated for ourselves. You have to learn how to crawl before you can run, so I would suggest you just grow them normally and when you have worked out a bit about what it takes to grow cannabis successfully, then explore new techniques such as "mainlining". Get an understanding of your equipment, nutrients, plant hygiene, your plants requirements, water quality and quantity and substrate function before adding another layer of complication on top of it all. It would really help you if you get a basic knowledge base first and not overload yourself with trying to do too much too soon. I am not saying it is impossible, but probably not needed just yet. Right now your questions reflect a basic level of what's involved (no disrespect intended!) and like I suggested, you should try and not make things overly complicated for yourself with your very first grow. There are a fair few basic principles to master, it is not quite "put them in dirt, feed them and water them, switch lights on and off and bingo, free buds! Anyway, they look almost ready for transplanting, maybe wait until they are on their third set of leaves. Pots of about 20 litres/5 gallons work fine. Definitely don't top them before transplanting them, wait until they have been transplanted plus at least another two weeks for them to settle into new strong growth before any topping is done and there are at least 5-8 nodes to chose from, remembering the very lowest two sets of branches never really grow that well and I generally remove them as soon as they are big enough to be seen. Just rub the stem or slide a fingernail down and they will be gone, no need to use a blade etc). Topping them will also cause them to slow down for another 10-14 days while they recover and work out what has just happened, and before they start growing normally again. I would also suggest starting your seeds next time in plastic pots. While those environmentally friendly pots seem like a great idea, in my experience with them, is that they take a very long time to break down enough to let the roots go freely. In the end I carefully cut slits in the sides to help the roots get out much faster and much more easily. I couldn't work out why my plants were growing so slowly, so I carefully dug up one of those cardboard pots to discover to my horror that they had basically not broken down at all and my plants roots were really struggling to break through the "eco pots" and into the fresh soil into which I had transplanted them into. Besides, the plastic pots, if treated with kindness, can be washed and re-used for many years, making them an almost "responsible" option environmentally. I worked out that the cardboard ones would only break down and allow unimpeded root growth if they were kept REALLY wet and soggy, which is something that cannabis does not like. The mysterious pH increases can sometimes be traced back to the material that the actual "air stone" is made out of and leaching lime/calcium into your water. It probably isn't overly harmful/critical, however, if you can find an airstone that is dark grey/black in colour (aquarium shop), they seem to be less reactive than the cheap blue/green ones. About your seedlings going limp after watering, it could be a reaction to whatever you are using to adjust the pH of your water. At this age/size, the seedlings are pretty fragile and I would be giving them plain tap water without anything added to it. If the tap water is fine for people to drink, your seedlings will be fine with it too. If you are really keen, just let the tap water in a bucket for 24-36 hours before using it and this will allow all the chlorine to evaporate before you use it. pH is not something that is overly critical when growing in soil and it is not a case of if it isn't exactly 6.8 your plants will die/not grow/not perform/be ok - as long as the pH range is somewhere between 6.0 and 7.4 your plants will grow just fine. Nutrient "lock out" in the true sense, does not occur unless your soil is below 5.0 or above 8.0 which is almost impossible to achieve without chemical intervention or gross mistakes. All these little things are all the little "crawling steps" you need to understand before you can run. Like most things in life, it often pays to keep things as simple as possible (or also known as the "KISS" principle), especially if it is your first grow. Do you have/ have you decided on which nutrients you will be feeding your girls? If not, following in the "keep it simple routine, "Flora Nova Grow one part and Flora Nova Bloom one part by GHE and Bio Vega (one part) and Bio Flores (one part) by Bio Canna are two lines that are super effective and super simple to use (but half strength is usually more than enough), that I can highly recommend. They are also all just one bottle complete fertilizers meaning no mixing or having to buy bottle B and/or C to make a complete product. They are all quite concentrated, so you don't need much and one bottle will last many, many plants or multiple grows. And no, I don't sell the stuff or work for either company, I just like recommending them because they work and they are simple to use. Congratulations if you made it this far and all the way through my ramblings, I am just keen for new growers to learn and not be put off by overly complicated or overly rigid ideas that might put them off growing all together. Feel free to message me if you like, I love helping people. Good luck with your grow, you have embarked on a journey that will bring you endless joy and endless learning. I have been learning for 35+ years and amaze myself with how much there is still to learn, as you never stop learning with cannabis cultivation. If you do, then you are not paying attention! Hope this helps,.... Organoman.