I would suggest to continue with the sitz baths, they were essential in the healing of my two prior surgeries. The healing time of both surgeries varied greatly, the 1st time it took 6 weeks to heal and the 2nd time it took 3 weeks to heal. Same procedure, same fistula. I guess it depends on the condition of your crohns at the time of your surgery. That's how i try to make sense of the different healing times.
32 yr old male
Diagnosed with Crohns in 1994 (lower bowel/ileum)
Medication history: prednisone, azacol, sulfasalazine, cipro
Current Medications: entocourt (periodically-as needed), Remicaid, flagyl
Surgeries: 2002 (remove fistula), 2004 (6" of ileum removed)