Is eating fruits and veggies only for 3 days after diverticulitis diagnosis ok? it was doc recommended.

Yes: Your doctor wants you to rest your bowels by eating food that is easy to digest and contains a lot of fibers. You should be ok by doing it.

I would wait: till fter the acute event subsides then begin your new diet.

Low fiber: Typically it is recommended to stick to a low fiber diet during and after an attack of diverticulitis, but this is only a recommendation. Once healed, a high fiber diet is beneficial.