Minimize the number of trips or Group maximum possible orders

We have one distribution center ( ware house ) and we are getting orders in real time whose time/distance taken ware house and the order locations is known.

time matrix= W O1 O2 O3 W 0 5 6 2 O1 5 0 20 7 O2 20 9 0 11 O3 2 7 11 0

order time of O1= 10:00 AM
order time of O2= 10:20  AM
order time of O3= 10:25 AM    

     I want to club as many as order possible such that delivery time of any order does not exceed by 2 hours of its order time.  Thus the question is to reduce the number of trips(Trip is when delivery agent goes for delivery).  

I am trying to come up with algorithm for this. there are two competing factors when    

1) We can combine all the orders in the sequence as they are coming till it satisfies the constraint of delivery of the order within 2 hours of its ordering time. 

2)  We can modify above approach to find the bottleneck order(due to which we can not club more order now in approach 1). and pull it out from trip1 and make it a part of trip 2(new order) and wait for other orders to club it with trip1 or trip2 depending.

All the orders are coming in realtime.  What will be the best approach to conquer this situation. Let me know if you need more clarity on this.