Ok to add sugar months into making cherry bounce?

I made a recipe for cherry bounce from Rum, fresh cherries, cinnamon sticks, vanilla bean and cloves. It did not call for sugar. I mixed it in jars in July and it’s been sitting since then in my dark pantry.

I tasted it and I think it definitely needs sugar. Is it too late to add it now or will it be ok to gift for Christmas if I added sugar now?

Thanks for your help!!