APY:
Specific details can of course be set by each community, shuls, school that implements. I simply outlined the model
The communities that have done it so far have used the follwing rules.
1. The community (or whomever was appointed to run the project) gave the money to the shadchan.
2. being that it was set up as date 2/4 if it didn’t go to 2 the shadchan didn’t get compensated. Whatever rules they set up they followed.
3. This is irrespective of shadchanus that comes from the family for completed shidduchim.
APY: feel free to implement it in your neighborhood with your ideas for improvements. Some communities might want to do it for date 1/date 4 (e.g. if they are a small out of town commuity for whose girls even getting to one date is difficult). some communities migh feel that date 4 is the same as date #2 and thus would want the higher compensation at date #8.
Clearly the specific paramaters are not set in stone. Each community, shul, school should adjust as per their specific circumstances. I have simply outlined what has been tried and tested.