Timing for first dose?

I do know it is different for everyone, and I've read TONS of these posts with this exact question....BUT I am traveling next week and would love some advice on when to start.

We are leaving to go to a waterpark with our kids for 3 days on Wednesday.

Do I:
Take it tonight (Wednesday) so I'll have my second dose the day we leave?
Wait till Sunday night (my original plan) and be on days 3-6 while we're at the water park?

I should note that I'm prone to motion sickness and will already be taking a dramamine for the water slides.