Last weekend I bought this tree

from a local bonsai nursery, and once I got it home, gave it a good water. I noticed that the soil absorbed the water extremely slowly, but I initally put it down to having been under watered.
However, this weekend I had a chance to have a good look at it, and I've noticed that the soil is extremely dense and sandy.


So aside from absorbing water slowly, it doesn't drain very well. The moisture in the second and third pictures was left from morning watering about 10 hours prior.
My question is should I consider repotting it, or will it remain healthy in its current mix? I've got it in an area with filtered sunlight that doesn't get too hot, but being in Sydney, is it the wrong time to try repotting?
Cheers!
Kit