when to move outside

hi everyone, i'm extremely new this, in fact this is my first attempt to grow outdoors, with no prior experience. I just have a few basic questions. I started with seeds i collected from a nice batch i had bought, i germinated them in a paper towel, planted them in small pots to begin with, and i filled the pots with a nice potting mix, and kept the soil damp with spring water. I then put the small pots in a shoe box and left them in my cupboard, i've kept them in there for a few days, and one has grown really tall already, but it only has a small yellowish leaf on the very end, i decided to move it outside this morning for some sun, can anybody let me know if i'm on the right track? thanks a lot.

well, it depends on were you live
in Canada its already started to snow
but I start my seeds in april then move them outside in may