i had to this wit my terrier which was 1, now his steady as a rock with them, first of let your dog sniff the ferrets let this go on for a couple of weeks, so he knows the scent, then get them out and hold them in front of him, put the ferrets in an area where they are safe put the dog on the lead, if he goes for them, make sure he knows he has done wrong, but dont be agressive, keep doing this for a period of time, and above all dont rush it, youve got a while till the season come round