The Core

I've had more luck with NameJet.

If you want to cover all the bases add Pool as well.

You'll only need to potentially start bidding once the domain is awarded to a single registrar. By putting in orders at multiple registrars you're just hedging your bets that you will be able to take part in the bidding process should any other parties be interested in the domain.

I thought services like snapnames covered all the registrars, or at least the major ones?

Yep, the likes of Snapnames and Pool have a base of loads of different registrars in order to use their shared registry service connection threads. ICANN registrars only contract with one dropcatching company though (as far as i'm aware these days) so ultimately when the domain does drop it will reside with just one ICANN registrar who may happen to be under contract to Snapnames or Pool or even a lone registrar catcher themselves.

If the domain is a .com or .net the drop time will be based on the registry location so it'll be US Eastern Time. Although I think Gandi is based in France so presumably they will list the drop times on their site in Central European Summer Time.