Bit far for me mate! I started taking her out with another dog about 10 month, i started slipping her about 11-12 month then, she took ages to catch her first one it was coming to the end of the season and all the strong ones were left and lamp shy, try start him on easy ones mate, my whippet gives the occasional yap when she knows they are getting away because she got so frustrated when trying to catch her first one!
Took her out last night and she gave a yap on on her first slip caught one on her 2nd slip and was silent for the rest of the night!