On celebrationday 'Kingsday' in the netherlands I got 2 insta's of two hongkong girls.

I approached them by asking directions, then small talked on how their celebrating day was going, smalltalk about school/work. They liked it and were smiling the whole time. I was talking to both, but 80% more looking/attention to the girl I find a little more attractive.

During like 5-10 mins of pleasant small talk, I learned they were in Amsterdam for only like 5 days. I said, well then, we should do something real quick. They agreed. Got their insta's and went about my day. This was yesterday, I didnt message yet.

Whats the smartest next move/text? Should I invite both, and flirt with only one. Or flirt with both for possible threesome? Only invite one for activity date? What kind of activity/date is best?