I changed my oil after the first ride. I still have the original filter - I just sprayed it from the inside with carb cleaner to clean it. Main thing is make sure it is not deformed and don't use a brush on it - you will mess up the mesh.
This is an opinionated issue (oil, what type, how often) - but here is my program:
I change the oil every 2 to 3 rides ( appx 8 hrs riding). I clean the filter every other time I change the oil. I use Castrol GTX and mix ( 50/50) 10/40 with 20/50 to get a 15/45. I have done alot of research and found no evidence that "motorcycle" oil has any special ingredients in it or is a better grade. Therefor I will not spend 300% more for it. Show me some proof and I will buy yamalube the rest of my life!
A p.s. on the strainer filter - an open end 15/16 fits it perfectly - it is a pain to get at - and there won't be anything in it-would not even bother unless you feel you have to.