Zoho Sheets find next available piece of data

Hi - Looking to see if anyone has done something similar to what I'm looking for. I'm pretty sure it can be done but I'm struggling to find the time to run through all the scenarios to test my theory.

I have a list of discount codes that I want to be able to apply to a CRM record when a certain action happens.

My plan is to put a list of codes into Zoho Sheets. Have a column for Allocated. When the CRM criteria is met Zoho Flow finds the first row where the "Allocated" column is blank and identifies that row and allocates the code and updates the allocated column to indicate it has been allocated.

I know Zoho Sheets can retrieve a row based on criteria. What I don't know is if it will always return the first row that meets that criteria, and if there are things I need to plan for.

Sharing of experience would be much appreciated.

Sally