Before I shaved my head for the first time seven years ago, I talked to my wife about it and she was supportive. I’m glad, because I wouldn’t have shaved if she didn’t want me to.
!Don’t even talk about it with them before you do.
17 years of running this site has taught me that 99% of men regretted discussing it with their spouse before shaving as it caused many of them to delay the inevitable. So I stand behind my advice to not discuss it before shaving.
It's also not that big of deal to shave it, regardless of how much hair you start with. Especially nowadays with so many men shaving their head.