If you use your entire home for the daycare, and don't have rooms that are used exclusively for daycare, approximately 25% of your rent will be a deduction for the business (based on the 40 hours per week that you mentioned).
When you enter your business into TurboTax, it will ask you if you have a home daycare. Be sure to answer that correctly to have it ask you the proper followup questions. You will enter the full amount for your rent and utilities, and TurboTax should be able to calculate the proper deduction. Only enter your rent and utilities for the months that you did daycare. For your hours, be sure to include additional time spent at your home when children are NOT there that you are doing work for the daycare. That includes time used to specifically clean up and prepare for the daycare, and time for record-keeping.
I also recommend reading the Family Child Care Record-Keeping Guide, by Tom Copeland.
