Present Perfect for future actions

[Marcin]

Hi,
I came across the following sentence:
Can we go home now? Yes, after I have bought some more tea.

In my grammar book I read that we can use Present Perfect Simple when we talk about uncompleted but expected actions. For example:
When he has finished his homework, his mother will let him go out.

Is it ok to use Present Perfect Simple when we want to refer to future actions like this?

[Alan]

Yes, perfectly acceptable!