Hi @stj1120
Just an FYI, but it's probably better to post these kind of questions on the Designer Discussions board as you're much more likely to get a quick response as there are so many more people on those boards compared to the London User Group Board.
To answer your requests, you will need to think about how you want to do this as a Month does not map perfectly to a week number, so it's not as simple and turning to a date and then doing a join. If you want to do the join based on the week number of the first week in that month then you can covert to a week number using this formula:
tonumber(DateTimeFormat([DateTime_Out],"%W"))
These posts might also be of interest to you:
https://community.alteryx.com/t5/Alteryx-Designer-Discussions/Convert-date-to-week-number-of-that-ye...
https://community.alteryx.com/t5/Alteryx-Designer-Discussions/Week-Number-Calculation/td-p/321991
Joe Lipski