First job, I had was 3 yrs to full partnership. Current job will take 5 yrs. I also received another offer prior to my current job at a place that was also 5 yrs to full partnership. I have worked at/heard of groups that offer 3 yrs or less to partnership like my first job and like the ones mentioned above, but there's some out there that will milk you for 5 as I've also experienced.
In my case(s), there were incremental raises at the end of the fiscal years progressing to partnership; however, they were not in increments equal to what full partners were making if you took the difference in income between junior employee status vs full partner and divided it by the number of years it took to make partner.
A word of caution to those who entering into pp jobs on partnership track. Most groups (including the ones I've been with) do not make you full partner until you complete a full calendar year of however many years it takes to make partner. For example, let's say you join a group this year out of fellowship with 3 yrs toward partnership. You start working in July 2017. 3 yrs to partnership means you'll be full partner in July 2020, right? As Lee Corso would say, "Not so fast my friend!" Many groups distribute partnership bonuses at the end of the calendar year. Therefore, you would have to put in three full calendar years before you're eligible for that. In this example, that wouldn't be until end of Dec. 2020 even though you've technically worked there for 3.5 yrs at that point.
These seemingly longer times to partnership track is yet another economic indicator of the current state of affairs with the supply and demand of labor in our field i.e. job market. From talking with former med school classmates, friends, and hospital colleagues in other specialties who went into private practice in their respective fields, 3 yrs to partnership would be an absolute stretch. There's plenty who make it in 2 yrs and some in even 1. I've never heard of any gas, rads, or derm groups where it take 5 yrs to make partner...