We found out as soon as we could and then I had follow up late scans at 34 weeks so we knew for sure it was a boy. I am so glad we did find out. I have absolutely no regrets. It really helped us in our mental prep for the baby.
However you have come a long way and if it just a spur of the moment decision on his part then you might regret finding out. Someone mentioned thinking about it for a week before you decide. This sounds like a good plan.