Lesson 7: 10:30
I think there is a mistake with the FDONM (First Date of Next Month) field.
FDONM: DateSerial(Year(Date()), Month(Date())+1,1) wouldnt work if Date() is on December.
Lets say Date() is December 15, 2022. FDONM would return January 1, 2022 instead of January 1, 2023.

Lesson 7: 12:34
Lets say a customer has a birthday on January 8, 2023. IsBDnm (Is Birthday Next Month) field wouldnt correctly detect that the customer has a birthday next month since the year of FDONM is 2022 instead of 2023.