At Nvidia, Main RSUs are subject to a 4-year vesting schedule:
25% vests in the 1st-year (25.00% annually)
25% vests in the 2nd-year (6.25% quarterly)
25% vests in the 3rd-year (6.25% quarterly)
25% vests in the 4th-year (6.25% quarterly)
Nvidia commonly refers to RSU as NSU (Nvidia Stock Unit). Although the name is different, it is the same as RSU's. Vesting dates throughout the year are standardized regardless of start date. Vesting occurs third Wednesdays in March, June and September, and on the second Wednesday in December.