VBA Help

Ive not been on for a while but Im really stuck with some vba i need to write in access and was wondering if anyone could help?

I have to write a routine that matches the schedule times of a public transport service to the actual times the service was observed, if I have 20 schedule times and 10 observations I need to determine the best fit so that the majority of those observations pass as many schedule slots as possible! Data must run sequentially, so schedule must run in order and observation times must also run in order against the schedule.

A pass is anything between -1 and +5 minutes, anything earlier is early and anything later is late.

My thoughts are that im going to have to loop through every eventuality and keep the highest pass rate but im not sure how to figure out every eventuality.

Ive already written code to select a specific service schedule and observations for that schedule.

Any help or even your thoughts are really appreciated.