Serissa foetida: On Watering

I bought this plant from a nursery last Sunday. It is still in its original soil mixture, which seems to be (too) high in humus matter, but with medium grit interspersed through out. It drains OK. I think I will repot it soon, and use a 60% lava/turface and 40% crushed pine bark. The current state of the soil is damp, but close to dry. The consensus seems to be that overwatering more quickly kills than underwatering in Serissa. Testing with the chopstick method, it comes out dry with a bit of moisture.

Now about the leaves. A number of them are browning at the tips, indicating that there is not enough water. On the other hand, some are yellow, a sign of overwatering. A few are "bubbly" or sort of wilted. The rest are green to rich green. I recently exposed a root in front as well as mounded up behind the tree to protect some damaged bark-turned-into-roots. Should I give it a 5-10 minute soak today?

Sorry for all the questions. This is my first bonsai.

i would leave it for awhile longer if there is still moisture in the soil...also, wait until spring to re-pot...everything i have read about this species says they are kinda fussy when it comes to their roots being messed with, so optimal timing is essential...

as far as the leaves go, to my understanding, they are a lot like ficus benjamina as far as positioning goes...by that i mean, they dont like being moved to new locations...this can stress the plant a bit and cause yellowing leaves and leaf drop...seeing as how you just got it last sunday, i would guess that it hasnt had a chance to acclimate itself to its new home...i would find a spot for it (no drafts, good light) where it can stay until spring without having to be moved and let it be for a bit...humidity will be of great help, so a light misting 1-2 times a day would probably be a good idea if the humidity levels are low...

keep an eye on the soil for moisture, but for now, i wouldnt water it since the plant is probably stressed and not really taking up much water anyway...watering it now would probably do more harm than good...i wouldnt do any fertilizing right now either...

maybe someone with experience with this species will chime in with more/better details...