Looking back at your prior posts, it looks like your rabbit is already 9 months of age. Unfortunately, if you have to wait another 5 or 6 months before he gets neutered, it's possible that his hormonal behaviors will become ingrained (permanent). It's a risk you'll be taking by waiting that long. There's no way to reduce that hormonal behavior outside of neutering, though the severity of the behavior has the potential to increase in intensity.
You may want to see if there's a way you can do some other side jobs or such to raise some funds before then, or see if you can make arrangements with someone to pay them back. Perhaps start with calling some local rabbit vets to get a price quote for the procedure so you'll know what amount will be needed. Prices can vary greatly depending on your location and the vet.
The price of a neuter should've been considered as part of "owning a rabbit" cost. Unfortunately, that isn't often explained to those buying a rabbit for the first time.