How to filter First order per unique person

#1
I have a fairly difficult question and I can't seem to solve it myself.

I am doing research for my internship. They gave me a database with every order they ever received. The research is about returning customers. One thing I would like to know is the product(s) people buy when they order for the first time per shop (they have multiple)

I made this little test file so it easier to test things with:
1559045446210.png

I already made it so only orders from Shop_A are showing.

Here is my question. I would like the file to only show the first product(s) that have been bought per person (unique_id). 1 order could have multiple items. For example for unique_id the number 1 is in it for 3 times. 1 order has been placed on the 28th of may 2019 and it contained 2 items. The second one was placed the 29th of may 2019. I would like to get the 2nd one removed. I would like this to happen for every single person (user_id)

I would really appreciate if someone could help me with this. If you have any question please let me know!
 

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