Automating A Survey Distribution - 60 to 90 days from initial response.

I have a bit of an unusual use case and I am looking for ideas to help either automating a survey distribution or making it more manageable if there is no automated option. 

The folks I am working with have some instructional materials posted on a website that they would like feedback on immediately after folks have viewed them, one month after they have viewed them, and 3 months after they have viewed them.  

• We are collecting immediate-post feedback via an anonymous link posted at the end of the materials. 
• We are collecting one-month post feedback by using a workflow triggered by completing the immediate-post survey that distributes the one-month post survey to an email address provided in the immediate-post survey. Those emails are also added to a contact list. 
• For the three-month post survey, I’d like to be able to use the distribution via a workflow method used for the one-month survey, but the timing on that is limited to 30 days from completion of the survey that triggers the workflow.  

My problem is that I have 53 of these surveys and not all respondents will be responding at the same time, so tracking and timing distribution of the survey will be difficult to do manually.  We’d also like to be able to connect all responses to all 3 survey responses by the email address they provide in the immediate-post survey, so any method I’d used would need a personally identifiable link. Can anyone think of any automated methods that would work?  If not, any ideas on making the manual workflow a little more manageable?

Thanks in advance.