XF 1.5 Import finishing

I import all but now i have last button what say "Complete Import", do i need to push this for finish or this is only when you rebuild?
I push one by one and all go well but do i nee to push "Complete Import" for finish or not?
Maybe noob question but i never do this before!

Yes, you need to complete the import, then do the rebuild tasks.
OK i test all and today i will import my forum. Its really easy to import(migrate). I have last question, what is the best way to do it, install xenforo, install theme(i will buy theme) then import forum(migrate from mybb to xenforo) or install xenforo, import mybb forum(migrate) and then install theme, add-on's......
What is the best way to do it??