Here's a wikipedia link that lays out all the JW and PQ convoy departure dates. However, I'm not sure even GWX simulates the Arctic convoys in this much detail.
http://en.wikipedia.org/wiki/Arctic_...f_World_War_II
Good luck on your attempt to interdict supplies to Uncle Joe. Bear in mind that the majority of Lend-Lease supplies eventually entered Russia through Vladivostok and the Persian corridor.