@Loh Jane,
It makes sense, would be better if you put a comma after ice cream, and after today.
Are you meaning you gave her ice cream on a day prior to today, blueberries today, and a treat in the future?
If I gave her both ice cream and blueberries today, I would have said...
Not only have I given my mom ice cream and blueberries today, I'll give her a treat on Mothers Day too.
If you had given the ice cream and blueberries on 2 separate days, I might say...
Not only have I given my mom ice cream and blueberries, I'm giving her a treat on Mother Day.