Thanks for the replies.
@Kanegasi
Thanks so much for this one; statistics are just another form of achievements, I would never have worked that one out.
@SDPhantom
Thanks for that, after a bit of testing I have found that base races have zero xp when they start but allied, DK and DH all have positive xp when they start, so I cannot use this as the best way of going forward.
I think I will stay with the time played >20 seconds, to account for the opening cinematic.
Cheers for the help