sending wait condition email

hi,

I am having two date fields A and B and an option set with values X, Y, Z .

Step 1:

when ever a record is created and date field A contains data and B does not contain data, I have to send an email depending on the option set selected . ( so there are 3 different kind of emails that needs to be sent depending on option set. If B contains date then no need to send email

Step 2: After 7 days from date field A, I have to do one more check to see if B is having date in it or not. If not I have to send  email depending on option set.

Any screen shots of the workflow for this requirement is highly appreciated.

Thanks