I would recommend getting airpots. They are much easier to clean and reuse, have a built-in space at the bottom to keep your grow media elevated for airflow and to keep it out of any standing runoff. They are also way easier to transplant out of if you go that route. They do cost a bit more, but they are way worth it. I'm on my 4th grow with the same set of airpots and while they are a little stained, I expect I could get another 10-15 grows out of them easily. Cloth pots like smart pots, however, are more disposable. It is very hard to transplant out of them without stressing the plant a lot. Roots grow into the fabric making it more effort to clean and reuse them. When I reused my cloth pots I had a huge algae problem the 2nd grow I used them for. not 100% sure why it happened but id assume because there was some algae in the cloth from the prior grow and it exploded the 2nd grow. after my 2nd harvest, the roots grew into the cloth so much that I couldn't get the root ball out without tearing or cutting the pots so I just tossed em and got my airpots.
Instead of using solo cups to start, use the smallest airpots. They are called propagation cells. They hold about 1 liter of growing media and will be large enough to last until around week 3 and then you should transplant. The final pots that I grow in are the #3 airpots that hold about 2.4 gallons. I prefer that size because I grow in coco and it allows more frequent watering. with soil you may want to go with a #5 airport which holds 3.3gal. The gallons they hold are on the smaller side because with airpots you don't need as much growing media to accommodate the roots due to air pruning. Air pruning will cause the roots to use every cubic inch of the pot for the root ball, unlike standard plastic pots.
You should start the seeds in a light soil mix so you don't overload them with nutrients. most seedling soil mixes will do, id personally go with something not super cheap but don't waste a ton of money either. just make sure you never buy miracle grow soil. most miracle grow has slow-release nutes that will cause all sorts of issues. a really popular brand that's not too expensive, if it is available near you, is fox farms. happy frog is their seedling soil and ocean forest is their nute heavy soil for vegging and blooming plants.
For nutes, it really depends on if you want to go organic or synthetic. For synthetic, I highly recommend skipping liquid nutes if you can. they tend to be overpriced and you are paying for mostly water. Look into megacrop or jacks 321 for some really solid dry nutrients that are fairly cheap and will last a looking time. I bought a 22lb bag of megacrop 2 years ago and am on my 6th grow with the same bag and still have enough for a 7th grow all for like $65. I also grow in coco which requires nutes the whole grow meaning i use a lot more than soil growers. $65 of liquid nutes might get you 2 grows in soil.
As far as growing on your balcony goes, make absolutely sure you have tons of direct sunlight. weed is an incredibly light hungry plant. hence why indoor growers give 18-20 hours of light on average during the veg cycle. The other guy mentioned having at least 5 hours of direct light, but I don't think that's enough. Id say you need a minimum of 8 hours of direct sunlight and ideally you would have 12+ hours in direct sunlight for the best results. If you don't get much sun on your balcony consider just growing inside as you will need to supplement extra light if you want to get more than just 5-10 grams maybe a little more.
another thing to consider with a balcony grow, are you in a legal state/country? if not, that plant is gonna smell when it flowers and your neighbors will deff smell it and if they are assholes, likely report it. so just be safe!
if you need anymore help or have any more questions about starting a grow, feel free to dm me! good luck!