My horse was very fit and was being ridden 5 times a week until July 1 when she got a superficial wound on a hind leg. It's 100% healed with hair grown back so tomorrow I'm going to start riding her again. How slow should I take it with her? 

Bump

If your horse was fit going into the stall rest , she won't lose very much fitness from one month off. Riding five times per week doesn't necessarily mean she was fit . I would start with one week of light riding , the next week increase length of time riding each day and go back to normal the third week.

Awesome, thank you so much!!!

she was actually turned out 24/7 and not on stall rest. I didn't think she'd be too far behind - thank you for your comment!!