How can i set a good sleep pattern of 3 months old baby? Is it even possible?

Yes it’s definitely possible to set a good sleep pattern at such a young age. You need to start a routine. I recommend starting by giving baby a shower, then a massage and change to pyjamas. 1 good night story. 1 lullaby and then tuck into cot with blanket and a bottle of milk. Repeat same routine every night at same time for one week. Baby should start falling into routine then. Good luck!