Pop Mart Berlin, looking for advice🙏

I’m visiting the Pop Mart store in Berlin for the first time tomorrow and will only be in the city for one day. I’d appreciate some tips from those who’ve been there. I’ve read that BIE, MAC, and HAS are only available at the checkout, with a limit of 6 blind boxes per person. I’m hoping to get 1 or 2 Labubu if I’m lucky (planning to arrive before opening to wait in line and increase my chances) and then use the rest of my limit for other IPs I collect.

If they sell out quickly, should I head straight to the counter? And if I buy them right away but haven’t reached the purchase limit, can I still look around and shop more, or does paying mean I have to leave? I’d be grateful if someone could explain how it works.