I wouldn't be able to help myself if I were you, I would divide it now...it looks really healthy, and I genuinely don't think doing it now would cause it any harm. Since you grow in a greenhouse, you're probably getting some active growth now anyways (I grow on a southern windowsill and I've got stuff growing like mad right now and its December!) so I really think it would be okay. Just my opinion though Just a note though - keep in mind that those air roots are just that - air roots. They might not like being repotted into media...they may rot, I dunno. I don't have a lot of air roots on my plants...so maybe just be careful? Don't pot them too deep and make sure they can dry out.