So smell it if possible.
For a very solid ice cream ideal for scooping onto cones, you may need to go as much as 6+ hours of freezing before the mango ice cream is ready.
I recommend to sieve it to ensure that there are no fibers in the puree.
First dissolve the sugar in 5 fl oz 150 ml water over a low heat until all the grains of sugar have disappeared, then turn the heat up a little bit and simmer gently for 15 minutes, without allowing the liquid to evaporate.