20 mins a day is fine mate,mine are lucky if they get 10 mins during the week when iam flat out.
HOWEVER.....i raised them all from kits and some from birth and i do put -A LOT -of time in during the first 6 months of their life, which is why i get away with it i think.The bonding and trust is done in that first 4-6 months imo. My advice would be do some research etc and get kits in. Its easier in a court etc during the summer months,for example i get in from work do the usual family stuff etc,then i grab a cuppa tea and me smokes and sit down the court for an hour.I have 15 min free for a