I have approved to affiliate with bluohost and hostmonter at cj. And in email i received from them, they said they will pay commision even first sale for my website.. So they will pay when i buy hosting with my own affiliated link?

NO They won't.

you will against their tos if you buy hosting with your own aff id.

in email i receive from bluehost affiliates there say:

Bluehost offers $90 per qualified sale! Your first sale (even for your own website) will result in a $90 commission and every sale thereafter

Well if it came from them then I guess it must be true.
I certainly wasnt aware of this, but am happy you bought it to my attention.
Thanks