At the risk of reopening an old thread, since I landed on this searching for info on RSU taxation when moving interstate I want to add that NY state rules around this are more complex (& painful) than mentioned in the other answers and could include more tax due for the OP in future years due to their NY dates and move.
There is a grant-to-vest rule for RSUs which bases the amount of New York source income for the RSUs on the number of days worked in New York during the entire grant-to-vest period. e.g. for a 3 year vest the fraction is based on days worked in NY divided by the total of days worked (likely hundreds) in those 3 years.
In the case of OP this calculation would be from the point the RSUs were granted so would include their days in California pre-move along with days they perhaps visited NY office as non-resident during those California years, and then of course racking up NY 'work days' after moving to NY with those still-unvested RSUs in hand.
Interesting article on it linked below, with detailed examples and also has discussion around the workday count [beyond the NY state worksheets on the topic]: “The Nuts and Bolts of Taxing Stock-Based Compensation in New York” (July 2022)
Link: https://www.hodgsonruss.com/assets/htmldocuments/The%20Nuts%20and%20Bolts%20of%20Taxing%20Stock-Base...
Hope this helps someone in the future, or at least @CoffeeBreak
