From scanning the forum (boy there are alot of posts!) I have found that any woody stemmed plant will do for a bonsai although it would be nice to know for sure (hopefully someone will answer my "Ivy" post).
In the meantime, when is a good time to start shaping my prospective bonsai? My ivy is approx. four inches high, I have been cutting back leaves and leaders for about a year now but it is still in just a regular pot. Should I repot it as a bonsai before shaping?