for starts you should never use clear plastic or light colored plastic like that white one either. you dont want light to get to your root systems. let em go in the till you see roots on the edge then get em outta there and into better pots. also its always a good idea just to start them in 1 gal planters this way you can let them get good and established and real healthy then transplant them to 3-5 pots. this way the shock from transplanting will be very minimal if any shock at all. I usually just lurk in the shadows around here but i been seeing this way to often lately and is becoming quite regular. if them aint fem seeds you really gotta watch this stuff or you will be ending up with a high male to female ratio. anyways as soon as you see roots making it to the edge of the soil/plastic transplant them. if you can go straight to your final pot size. stressing them this young is enough let alone stressing them multiple times trying to get up to a decent size pot. btw, when you transplant make sure to steralize the new pots good. this can be done simply by taking the new ones putting them in the kitchen sink under hot water and washing them with DISHSOAP not any other kind of soap. i would venture to guess you'll be doing this in about 2 1/2 - 3 weeks. also for the time being put some hole in the bottom of them containers for drainage if you havent already done so.