I am assembling snipes for much wanted ebay items. Should I activate the snipe now or wait until just before the auction closes to activate?

I don't want to unnecessarily raise the bid, but it would be so much more convenient if I could set it to start sniping two minutes before the end of the auction and forget about it.

Why would you want to set and forget and then wait until the last two minutes at the same time?
In my meaning "set and forget" means you set the snipe days before auction ends and forget about it.