My DS used to hate tummy time too untill i discovered the joys of baby massage! At mothers group we massaged their fronts, legs and arms and then turned them over to do their backs and I thought DS would scream but he loved it and then spent about 5 mins pushing himself up and looking around much to my amazement! Now he really enjoys it and will do 5 or more mins at a time- thats big for me cos he used to scream after 10 seconds
Good luck
xox