Yes, you want a small tree to spend its energy growing larger and not producing fruit. I don’t think flowers take that much energy but trying to ripen a fruit with all that sugar takes a lot from a tree. It should have a stout trunk and complex full canopy before it carries fruit. That usually means 2-3 years for a 3 gallon size. Dwarf Hawaiian is a smaller mango so it might be able to hold a few fruit next year if it grows well. My unscientific way of looking at it is to ask myself does the tree have a decent size (3x3’ or 4x4’) canopy and when I push on the trunk, does it move around or is it well planted in the ground?
There are some good YouTube videos of Richard Campbell talking about fruiting mangoes.
As an example, I grafted my Angie (semi-dwarf variety) in 2020 and allowed it to fruit in 2021 (bad idea). This is what it looked like. It held maybe 5 fruit to maturity and 3 were eaten by raccoons. The fruits didn’t taste very good which left me thinking if I chose a bad variety.
2022 was a bad year for everyone and I had no fruits that made it to maturity which meant the tree switched the vegetative growth in late spring. The tree flushed several times and doubled in height and width that year.
In 2023, the trunk was 4-5” diameter and canopy was easily 6’x6’. I had around 30 fruits that tasted amazing: