What setup when second survey should start after external event

[iunda...@gmail.com]

Hi all

I'm looking for advice for how to organize a run for the following setup:

1. Participants fill in survey 1
2. Researchers evaluate answers (can take several weeks)
   
3. When evaluation is done, researchers send participants an email invitation for survey 2
   
4. Participants fill in survey 2

So far, I was considering two possibilities to program this:

1. Use a stop point after survey 1. When the evaluation is finished, researchers send users manually to step 3 (email invitation) in the "Users" menu of the run module. This should work but I think it's not ideal that researchers need to login in, identify participants, and then send them manually to the correct step in the process. Seems too error prone.
   
2. Add an additional survey in which the researchers can indicate that the evaluation is finished (link could be sent via email and then be kept in email inbox until evaluation is finished). Once the researchers have confirmed the end of the evaluation, participants receive an email invitation for survey 2. This seems the more elegant way but I'm not sure how to set this up as a run. How do I prevent participants from directly continuing to Survey 2? Should I use a "Pause" or "Waiting Time" after Survey 1? Or somehow combine a "Stop Point" with a "Forward Skip"?
   

I would very much appreciate some opinions on which of these approaches (or any other) would work best (be least error prone) for my setup. I'd also be grateful for suggestions to implement approach 2.

 Best,

Adrian