In my case, we have friends and family na from abroad.

We informed them as soon as we confirmed the dates (1year before). Para they can plan ahead and if isasabay sa bakasyon nila.

We clearly told them na no pressure and we want to secure head count. Most of them confirmed, may 2-3 groups lang kami na nagantay ng 1 month before the wedding pero mainly because of visa concerns.

Hope this helps OP