ohhhh, THOSE plants... they look a little better. id say they are short of a month, probably not much. and as for when to flower, depends on lighting and space. if your using hps and have space let it roll on. if your using cfls you probably dont wanna wait more than a couple more weeks and you could easily flower now. best to flower under cfls a little early, especially if you dont have a lot of em as they dont have great penetration.