Sorry I am not of any help. But I couldn't find any official place either. When I googled my area DO, I found a local immigration lawyer's blog with oath dates for my DO(I am in a weird place where I have two DOs that have jurisdiction over me-San Diego and Chula Vista-but my NOA says San Diego).
I just wonder how to find out which DOs offer same day oaths and why etc.? Non of the CA Dos seem to offer same day oaths. I don't know about Houston.