There isn't any true source for open houses. Some agents advertise them, some not. You're looking at a pot luck situation driving around to locate them. Then the question becomes are you looking at a house that suits your needs? Price range? Floor plan etc...
My suggestion is to preview some of the homes online in the price points you're interested in, then set an appointment with an agent to preview those homes. Can be scheduled in one day. This way you don't waste your time and gas...
The other situation you run into is trying to deal directly with a listing agent who has obligations to the homeowner to sell you the house at the highest price possible. Who then will negotiate on your behalf???
You may want to consider using a "buyer's agent" to work on your behalf. There is absolutely no cost to you!
Above is a link to current homes in 33626.
Yours to count on,