No weight added at all for the first flight - I left the built-in weight on. I went for the Sierra tail wheel but took care to use aluminium bolts on the back to mount it and the lightest 3" foam wheel I could get my hands on.
Still, it flew OK but slightly tailheavy. For the next session, I have added about 200gr of fine lead shot in the cowl ring to shift the CG a bit fwd - TF birds lock-in nicely when nose-heavy..