Ultrasound showed gallbladder full of stones. had ruq pain on/off for few months. is surgery really needed? if yes, how quickly?

Yes : You have pains for few months , symptomatic gall bladder disease with stones , unlikely to get better with out surgery , plan it in next couple of months . It is a low risk ambulatory procedure , speak to your surgeon

Probably.: If your pain was ever accompanied by intermittent fever, nausea, vomiting or an elevated white blood count, i recommend you have it removed soon. Since you have had multiple episodes of pain only, with a gall bladder full of stones and young at 36 years old, i also would recommend you have it removed. With minimally invasive techniques it is safer than waiting until you get sick.