That small fan is what I've got in mine from an old computer that I scrapped out. It's a 12v. fan so I had to use a small power supply, but same basic thing. I also started out with 3 bulbs, then dropped down to 2 with a lower wattage. Those 3- 100w bulbs are capable of pushing my temp upwards of 150 deg.F which is way, way, too much! Slow and easy is the key I believe.
I'll pass along some advice from another member who uses a hot box for his Osage staves.
He said 80deg. for 2-3 weeks, then 90deg. for 2-3 weeks, after that your on your own.
Course if the outside temp is over 80deg. then you would need it a few deg. warmer possibly?
I'd just try 1 stave first to see how it reacts, then add more when you get the process perfected. That way you don't over cook all your staves at once.