I agree with the others - skip the bottle.
You'll figure out your own comfort level with the mixing formula and milk. We did increasing percentages - mainly just to make sure our son didn't have allergies.
A note on sippy cups. As new parents we had no idea the difference between sippy mechanisms. I would advise starting with two styles. Our son wouldn't do the "straw" style recommended for newbies, but he did great on the NUK ones that he squezzes the sippy part to open the valve. We mistakenly bought more, but those had a suction sippy part - he didn't take to that either.
My point is that you may run into some adjustments getting the right sippy cup - but don't let that deter you. After a few days - we put away all the bottles (two days ago in fact), and now he's on 100% vitamin D (whole) milk.