Couple of suggestions. One of them his preschool teacher helped me with. His preschool teacher last year made a surprise box (shoe box with dollar tree toys in it). Once he had his nails trimmed, he could look inside the surprise box and choose a toy.

Another thing I did was tell him "First trim nails, then you can play with trains (whatever your child's favorite toy/activity/movie is).

Sometimes both of those methods worked. One time we were on vacation and the room had really good back lighting when he was asleep and I was able to do it then.

I hope those help.

I just wait until he's asleep and do it without a problem. It's better if you wait about 15-20 min after they fall asleep. I always do it at night.

I have to cut my kids nails while there asleep. Sometimes one nail every 30 minutes.

For years and years I had to cut my daughter's nails when she was asleep and even then she had to be in a very deep sleep or she would wake up and want me to stop. Finally at 10 years old she allows me to trim her nails. I said you know Mama loves you, you have to trust me and let me cut your nails. Sometimes still, we will do a few nails one day and finish the next. I think sensory wise it is hard for her to tolerate but she is getting better and better with it!

I learned not to say "cut" - I say "trim". To my son, a "cut" is an owie so I don't use that word for fingernails, toenails or hair : )