Do you mean your daughter was born in March and you already have her, or you picked the name back in March and are questioning your decision closer to her arrival?
If you haven’t had her yet, my honest opinion is that Acelynn would likely get a lot of misspellings and possibly even mispronunciations through her life. It’s not a terrible name, but I’m not sure it’s the most wearable? I would pronounce it how it’s spelled, but I could see others calling her AS-a-lyn or AY-sa-lyn instead of Ace-lynn.
If you’ve already had her, that makes it trickier, but if she’s at most 6-7 months old, I still think you could change if you want to.
To offer alternatives, what about Azalea or Athena? Not names that you hear every day but are likely more recognizable. I think even “Icelynn” might be easier.
Lastly I do think two involved parents should have a say in the name (I do think Mom gets the edge in the end, but believe both parents should at least like the name even if they don’t both love it). Does he like any “A” names or anything else unique?
Good luck with whatever you choose!