I'm not going to tell my boyfriend when I'll be home.
Why don't you want to tell him when you'll be home?
I want him to be shocked because I will arrive earlier than expected.
I think it's fine to not tell your boyfriend when you'll be home, because he'll be happy when you come home earlier than expected. I'm sure he'll appreciate the surprise.
I definitely think he will appreciate it!
It's good that you're so nice to your boyfriend. I hope he enjoys it!