I don't post regular open or close hours anymore either. And when I have to... like on daycare bear... i make them them reasonable and post that extended hours are available.

My door is open and unlocked 10 min before arrival for drop off and pick up and parents know they are welcome to walk in. I think this makes my house seem welcome.... it also makes my house seem unwelcome if they have to ring the doorbell. Makes them think that I'm not expecting them.