Public Transit with different criteria than earliest arrival time

I have one question related to public transit routing.

I want to reach destination early but not at the cost of walking more.
I would like to catch a bus coming near to me because as it saves my total travel time. I could do something else for half an hour and then catch a bus which will be take me to destination without walking much. Do you have any suggestions how can I incorporate this in GTFS module? One approach in my mind is saving total travel time as bus will always be faster than walking - I want to reduce total travel time I am spending instead of reaching it as earliest.

Do you have any suggestions how can I incorporate this in GTFS module?