I have one friend who did sucessfully right from day one.
BUT, day 1 to around 2 weeks, was one bottle during the night, then from 2 to 4 weeks she did two bottles during the late evening (a DF probably) and at night....and so on.
By 4 mths she had her DS (no2, the first was not a successful combined feeder) on 4 hr easy with the 7am, 11am and 7 pm from breast and the 3pm and df formula only....
She then dropped the 11am to formula as well when she went back to work but did pump in work - he was around 6 mths when this happened - but sucessfully kept up the 7am and 7pm till 12 mths!
She says herself she was very lucky with her DS 2 - he was very sucky and didn't mind what he sucked....DS 1 got lazy and rejected the breast at 4-6 weeks and was fully ff by 3 mths (she pumped EBM and gave what she could till then).
As for mine - I EBF but used bottles a lot with Ozzie - one a day from around 2 weeks (ebm DF from DH) and then I was back in work fulltime from 4 mths so he was having 2-3 bottles a day....and again, he was fine, never batted an eyelid going from one to the other.
Emma was a totally different story. Number one, due to tongue tie, number two, she is much more sensitive to change, not as sucky as him, and because I was much much more scared of nipple confusion due to the tt and her sensitive nature that I gave up with bottles for DF very early on....
Hope that helps xxx