first grow need some advice

hey guys this is my first real grow ive picked the soil road i germinated my seed 3 of them from a plant a friend has.. i need to know about how long they should stay in what size containers i started in Dixie cups for like beer pong size.. 2 got to be about 4-5 inches in a few weeks the third got to about 6-8 they stopped growin taller so i moved them to a bigger home took old 2 liters washed and cut the tops off made sure for proper water drainage in the bottoms .....i also could be doin something wrong past few days the bottom 2 sets of leaves have started to yellow and die and fall off is this normal or do i need to do something about it when they started i would mist them a few times a day lightly but none the less they still died the rest of the plants look great tho the smaller 2 have a little redish purple thing goin on with the main i guess u would call trunk like a tree lol but the big one grew out of it so i dont think this is a concern all help or tips would be greatly appreciated
thx, chim

you should go with 5 gallon buckets as everytime you transplant them to bigger containers they get shocked and waste energy adapt to the change which could be used for growing also the less you bother the plant the better and gives plenty room for root growth is what you want the more roots the better and bigger the plant

Stop misting,your killing them
Bottom 2 leaf do fall off but not at your stage,bigger pots = bigger plants,im a hydro person and from what ive read 10Litre up is what you want.
These guys are nearly ready for nutes,stop misting,you should mist once a week.

Some one else will be along to help you on soil and stuff but id say go staight in to 15Litre,It depends on what size your after.

You need to keep light close on babbys or they will stretch,you want short tight nodes between branches not big tall plants with massive spacing between nodes.

A lot of people here willing to help,I think ive covered your problems but again im a hydro man so a soil man needs to advise you.