I don't think 20oz is too much considering he can't have dairy solids yet. Although guidance is to drop bottles at 1yo many continue with 1 or 2 bottles per day for a long time after and in your case it makes sense to have a third milk drink. Are you worried about the amount of milk or that he is still having the bottles?
What is he like if you give the morning milk at WU and the solids an hour or so later? Mine still has a big milk drink (cup but he is much older) first thing before his breakfast, I see it as a very quick method of getting something in his tummy, far more immediate than solids breakfast.