Not sure what you mean -
If you're asking how far ahead can we put in a backorder for a domain, some will let you do it to any domain, even if there is 10 years on the registration. I have one domain registered until 2020 and I can backorder it - they just don't show a date when it'll become available.
I get daily emails from Pool about domains dropping with specifick keywords, they usually appear on the list 5 days before the name drops.