New butcher block typically gets passed thru a thickness planer after glue-up so I don't think you can sand it too smooth.

There's lots of detailed info in the attached article on refinishing & caring for BB cutting boards. I'm glad you asked this question because it reminded me that I need to hunt down the mineral oil for my cutting board.

Here is a link that might be useful: Refinishing Butcher Block

Ci_lantro, that is the best article about caring for butcher block that I've ever read--I'm going to save it. Thanks so much!

I ended up just going to 150 grit sandpaper and leaving it at that. I had seen some brand-new boards at Williams-Sonoma, and they weren't anywhere near smooth.

I had every intention for sanding ours smoother then 150, but then my evil twin, lazy jess, took over. I am glad that I didn't because I have been keeping a piece of 150 sandpaper in the drawer to sand out the occasionally spot. with leaving it a 150 you can't feel were I did that.

Hopping on to an old thread here, but I am wondering about this. I just sanded my new (old, used) butcher block to 150 grit, oiled it twice, and I'm finding the finish a bit rougher than I had hoped. Can I sand to 220 right after oiling it, or do I need to wait a while?

I would wait a while and let it dry out a bit, otherwise the 220 will gum up with oil.
Or, wash it down with lemon juice and salt to speed up process...