Plotting monthly average over time of a column grouped by another column - RStudio

Question

I have a dataframe df_have that looks like this:

  Arrival_Date     Cust_ID      Wait_Time_Mins    Cust_Priority 
  <chr>              <int>          <int>           <int> 
1 1/01/2010         612345            114               1 
2 1/01/2010         415911            146               4 
3 1/01/2010         445132             13               2 
4 1/01/2010         515619             72               3 
5 1/01/2010         725521            155               4 
6 1/01/2010         401404            100               5 
    ...               ...              ...             ...   

And I want to create five line graphs - 1 for each of the unique values in Cust_Priority - overlayed on the same plot, such that it is the such that it is the average Wait_Time_Mins by Cust_Priority by month.

How would I do this?

I know how