We started tummy time at 2 weeks old based on our pediatrician's recommendation. Our baby hated it too, cried through it everytime. I would let her go until she really cried. Mostly at first she would just kind of fuss, but 5 min start really crying (i.e., face planted flat and crying). That was when I would stop. I would then turn on some music and pick her up and we would dance to a song or two. She loved it! We did it 2-3 times a day for about 5 min at a time. Now she is almost 3 months and we do tummy time 4+ times a day for 15-20 min at a time. I use the same gauge...once she starts really crying, we stop. Sometimes she does all 15-20 min flat on the activity mat without fussing. But later in the day, she fusses after 5 min. So, for that round, I start with the first 5 min flat, next 5 min propped on a boppy (breastfeeding pillow), and the last 5 min on my chest, reclined in the chair. Trust me, I was skeptical at first, but your baby will get better at it and actually start enjoying it eventually because its a different point of view than lying on their back all day. They also enjoy being propped up in a sitting position either with you holding them, or propped with pillows (always supervised and when they are a little older, like 2+ months). This also helps them work their neck muscles because they will hold their head steady while sitting up. Because we started at 2 weeks, our baby at 2.5 months rolled over from tummy to back on her own and could hold her head at 90 degrees while on tummy. She's now close to rolling from back to tummy at 3 months. She can also hold her head upright when you pull her up by her arms when lying down. You really must do it (unless medically unable) because it's important. And the earlier they start, the more they will like it later (2+ months) when it becomes really important.