You can change the formula in E20 to this:

=IF(AND(D20="Canada",A20>=$G$18,A20<=EOMONTH($G$18,2)),MAX(E$19:E19)+1,"-")

(note the change in red) in order to include 2 months in addition to the starting month - just copy this down and the secondary table will give the same results as yours.

Hope this helps.

Pete