When should I plant germinating seeds?

Plant now, as soon as you can see the root starting. This will limit any potential to damage the root if left to grow too long. Please use decent pots, "tiny pre veg pots" will just limit their development and stunt them. Ideally, black plastic pots about 4 inches across and 5 inches deep are perfect for seedlings for about 3 weeks. If you want big plants, you can't start them in thimble sized pots, the roots will hit the bottom in 2-4 days and signal the plant to slow down as it will think it is already running out of room. To see the root system of a 3 week old seedling and get an appreciation as to why deep pots are necessary for proper root development, go to week 7 in my diary "cannabis conundrums" and you will find pictures of the exposed root system, along with many other interesting cannabis pictures if you are keen for an insight into why deep pots are so vital for early development of seedlings. More roots = more plant. It really is that simple! Hope this helps, Organoman.