Hey, I would say move it at increments of 1 hour a day. Example: If right now you have it at:turn on at 8am, turn off at 8pm, then.. Day 1: turn on at 7am, off at 7pm, day 2: on at 6am, off at 6pm
In my opinion, this won't help your temperature problem much...especially since I assume you are getting your intake air from indoors..which is usually cooled less at night. In the meantime, use fungicide sprays and there are a few science experiment type things you can try to cool the area. One video example I saw is a paper plate w/ ice + salt covered in aluminum foil with holes in it--you can find that by googling homemade air conditioner or something.