So, I'm trying to order spokes for my new wheels and I'm kind of stressed out. I'm trying to lace Phil Wood, large flange, one-sided track hubs to a set of 32-hole DT Swiss r1.1 rims. Some things say 288mm, others say 290mm. Is this a big difference? How much fudge-room do I have with spoke length?
Anyone built up this combination before? Advice? Inspiration (other than how sweet the combination will be)? Thanks

try spocalc

https://www.damonrinard.com/spocalc.htm

Did you do the measuring yourself? I've rounded down an mm when using the free spoke calculator. What do YOUR measurements give you? If you've got longer spokes, they may stick out past the nipple when you've got things all tensioned up, but it won't be that big of a deal if you're running some deeper dish rims. If you run the spokes too short, you may not be able to get enough spoke/nipple engagement. I've read on these forums you can go 2mm either way, but YMMV. Whenever I'm calculating spoke lengths, if find it very hard to vary my hub measurements to give me a 2mm difference.