I'd have it done now. From what I understand, a snip at a very young age is a quick and easy procedure, relatively painless, and is only very rarely associated with complications.
DS2 was initially diagnosed with tongue tie at 6 weeks (only because I pointed it out!) GP was reluctant to refer as DS2 was gaining weight really well, and we had no issues with feeding. However, at about 3 months, feeding became a big problem when DS2 started flailing at the breast and refusing to feed. He lost weight rapidly, and plunged through 2 centile lines.
After a fairly quick referral by a lactation consultant to a maxfax surgeon, DS2 had his tie separated at about 4.5 months, under general anaesthetic.
The surgery and recovery was awful. DS2 refused to feed for several days, and was in a lot of pain . However, when DS2 resumed feeding, boy, did he feed! The difference was huge. His weight has increased significantly, and he is now back on the centile line he was following at birth.
We think that it was left too late, and if it had been done when first diagnosed, the weight loss and post-operative pain DS2 endured would have been avoided . The lactation consultant agreed with me and was horrified that the referral had been left so late.
So, in your position, and knowing my experience, I would definately have it done now, rather than wait and see.
Sorry for long post, but I hope that it's of some help.