Push-ups on parallel bars can practice dumbbells according to your own situation. If you have no foundation, try to do five push-ups at a time, and each one should be standard. If you can't even push-ups, you must use dumbbells first. At the beginning, it was just a lift, asking for+other actions. Slowly+measure. For example, push-ups from 10+ to 15.5+ are more scientific.
Of course, it must be done every day, even if it is only a group (5), it will be useful.
As for how long,
I have been practicing since the first grade. Up to now, I can do about 0/00 push-ups/kloc, and 450 sit-ups intermittently. Of course, I don't do this every day. I believe that if you persist in doing it every day, you can develop obvious muscles in about 2 years. Abdominal muscles grow faster than those on the arms. )