Min time stamp partition by same value in column

I have a below dataset where I’m trying to get the min timestamp of the same values in a single column.

Here is my dataset.

I am trying to create a column to find user_first_comment for each interaction with dealer.

like below

is there any technique that i can use to add a incremental value for same values in columns. for example column RANK_Incremental,so that i can use Min wit hpartition to get final output.