If you bid manually just try and do it with about 10-20 seconds left. If you do it minutes in advance you'll be tipping your hand and inviting other bidders to increase their maximum which could cause you to lose or pay a higher price.
You cant outbid yourself, so you could bid from home, your spouse from work, your kids from school, and have a snipe in with us if you wanted to be extra safe. I would not encourage letting your dog place a snipe though, that would be pushing it