How to make my message sound polite?

[Mariana95]

Not really AIBU but I want my message to come across the right way.

I have a tradesman who's an acquaintance/casual friend coming to do some work in my house at the end of the month. He'll liaise with me and my housemates to find a suitable day.

I wanted to send a message saying, "you can start on the 28/08 is fine if you like, as I'll be out of the house all day, and I'll only be back briefly at around 4pm to collect a bag."
Does this sound like I'm implying, 'it's fine for you to come round then because I'm not there, and I don't want to see you'. The man is a friend, and it isn't a big deal, but I don't want to sound rude either.

Maybe I'm just overthinking.

“I’d appreciate you starting on the 28th as we will be out of your way for most of the day” will be fine and not rude.

Maybe just rephrase it if you're worried? Maybe something like "Are you able to fit us in on 28th August, please? I won't be in, but you can catch me on my mobile if you need me and I'll be popping home around 4pm. Help yourself to tea and coffee"?