How long tummy time for 2 months old

Hi mummies, how long should i do tummy time for my 2 months old baby? He’s still not able to lift his head and would cry murder every tummy time which lasted 2-3 mins only. How many times a day and how long each session. Any other ways to tummy time other than flat on tummy on bed or floor. Ive tried putting black white cards infront bt he can’t lift his head to look at it yet. If baby cry murder should i stop or leave him. However when i carry him over shoulder he likes to lift his head off my shoulder. Is that considered as strengthening his neck too? #firsttimemom #pleasehelp