I'm not sure about the cut off although I am sure some of the other ladies woudl know. My son was born at almost 32 weeks. So until he was two years old, when talking about milestones, they'd put him at 8-9 weeks younger than his gestational age. So say, if a bub is 'supposed' to do something at 8 weeks, they'd look to see that ds was doing it by 8+8weeks = 16 weeks of age.
It essentially 'bought' him a bit more time to do things!
Although I thought the cut off for doing this was around your babies age and after that they don't do it...so given yuor daughter was almost 'full term' (36+ weeks) they may not correct her age. Not sure though - your paed shoudl be able to tell you how they will apprach your little one.