Needing to find how many days it took to provide service after an admission date. problem is that many service dates are there after the admission date. How do I only pull the first date after the admission for each client?

ClientID, admiss_date,first_serv_date,datediff(dy,first_serv_date,admiss_date)

First_serv_date needs to be created somehow. Any tips? Thanks in advance.

Tried to pull the top 1 ranking, but it’s pulling the first service date regardless of client.