NJ employed and resident - how to allocate NY Taxes for bonus withheld from 3 years ago when employed in NY

[NJ Filer]

My employer withholds a portion of my bonus each year, and then pays it back three years later. In 2021, I was working in NYC, but living in NJ when the portion of my bonus was withheld by my employer. My role allowed me to work from NJ since 2023 and have never stepped foot in NY again. In 2024, when my withheld bonus was paid out in, NY taxes were withheld since I had earned that bonus when I was employed in NY and now I have to file NY Non-resident Form. But what  allocation method do I use for my NY wages? Do allocate by Percentage (divide withheld bonus money against total comp?) Or do I allocate over multiple years using IT-203-F?

PS. The instructions for IT-203-F are atrocious.  

Thanks in advance for any help!

[MaryK4]

You can use the percentage if the bonus only covers one year.   

[NJ Filer]

Thank you for your answer.  A follow up question: If the value of the bonus was X when it was held back, and now the value is Y when it was paid. Which value should one use to calculate the percent?