Mike is wanting to repot them from his 'gang rooting' pot (where they are all huddling together making roots) and was asking when it is time to give them their own pot (as in: are rooted). That is usually indicated by vigorous leaf growth.
If you want to move an existing (already rooted) plant outside, or step up from one size pot to the next, it is recommended to do this in the dormant stage or when they are just breaking dormancy so you don't break off too many of the feeder roots in the process.
