I’d say divided them no later than at 12 weeks. The fence in the middle need to be double with an inch or so disance between them, or very fine grid to prevent biting through the grids. This will not make a post-neuter bond harder. What will make a post bond (which is a true bond) harder is if they get into a fight before being neutered. Fighting can prevent a true bond from ever forming.
Rabbits can go from sweet and cuddly to a ball of fury in an instant. We cant know if your boys will mature now or much later, but I personally wouldnt risk fighting. Bonding two males can be difficult even when the buns are neutered. A situation like yours has the best chances of working out, provided the buns are separated before any fighting occurs.
Once your buns are neutered, you should wait one months before you start bun-to-bun bonding. Meanwhile you can do pre-bonding, meaning you switch their litterboxes between them, then switch their resp areas between them.
I had two neutered males that I was unable to bond despite serious efforts (they wanted to kill each other). It was both sad and very impractical.