I do know what you mean where that is concerned, biglouis. I am a firm believer in one's home being one's refuge, and that we should be able to do as we like within our own walls without feeling answerable to others. I wouldn't encourage anyone to turn up with shampoo and a towel at random times.
I would offer a 'slot', probably early evening, which was convenient for both us and them, and would expect them to keep to that time. I am one who sometimes loafs about in PJs, and wouldn't want a random neighbour knowing that information
. If I knew they were coming at 6.30pm, however, I would make sure I was presentable (I usually am by lunchtime anyway).