Inquiry about treatment for freckles after traveling to Southeast Asia

hello.

I am worried because my freckles have darkened due to the strong UV rays after traveling to Southeast Asia.

I tried to take care of my sunscreen, but it seems like it wasn't enough.
What I'm curious about is this

I have to go again in late January.
I would like to ask whether I should start treatment for my melasma in my current condition or whether it would be better to start it after I return from my scheduled visit to Southeast Asia in January.

I am concerned that exposure to strong UV rays immediately after treatment may worsen pigmentation.
If I start treatment after my trip, could you please give me some simple home care recommendations to help keep my freckles from getting darker until then?