Hey Lost,
I also had a fissure for 8 months before getting LIS, and I can tell you right now if I had known what I know now and had been diagnosed early enough, I would have had LIS after 6 weeks of my fissure. Unfortunately I wasn't diagnosed until I had mine for about 4 months.
If I would have been diagnosed as quickly as you have, I would have gave the ointment and baths about 6 weeks and if that didn't work then I would have went ahead with my surgery.
The ointments can take awhile to heal. Some have healed with the ointments after a few months and some years, but from what I read most who healed were prescribed the ointment right away as you have been.
You could use this time to get the diet/ and or stool softeners, fiber or whatever makes your bm's come religiously and soft before you get your Lis (if needed) . It really does take some trial and error while figuring out the best diet and supplements make the best bm's for healing...
It is definitely a personal decision on how long you can take it or willing to wait before the surgery. Most of us were so fearful of the surgery that we gave it much longer than we should have, Lol
Good luck and try to take the warm baths. They really help along with the diet, softeners and ointment.