Container question

hey guys, i was just wondering how long I would be able to keep my plants in a 1.4liter container? I have 10 plants all 5 days old (since they shot out of the soil) I hoped to keep them in the pots til I could make a couple of clones to determine sex, but the more I read the more im thinking I wont be able to >_<, So any idea??? I wanna make sure they don't get root bound >_>,

Also on my first grow (and first failure) I tried to transplant into bigger containers, but the soil was so compact it just would not come out of the pot, I ended up completely fuckin the root system up and just having alot of dirt, everywhere! So whats the best transplanting technique??

Thanks!

keep them in the 1.4 container till there 15 inches then trans plant. when trans planting water the plant well then tip out the old container in to the new, then once transfered water well again. the watering reduces stress to the plant.