First outdoor grow - Need help

This is my first time posting to this forum on grasscity and this is also the first time ive tried growing. so heres what ive done so far......i have 5 feminized auto flowering seeds that i germinated with the paper towel method and that was a success. a few days ago i transported the seedlings to solo cups and now there sitting in a shed next to a window. untill i plant them in their pots, this will where i was planning on keeping them. im at the stage now where im waiting for the plants to grow a bit more before moving them to their final grow medium.

what i want to know is what i should be doing next.....how do i knnow when the plants are strong enough to live outside? what supplements should i be using? and if there is any other tips that anyone can suggest, please share.