A small victory and a very busy little bitch sub

Today I've had subby a very busy little bitch. So far sent out for 3 assignments and completed them all better than I commanded. This morning was the first. He assisted mistress Y a fellow domme with a female sub, he was there for the session to provide oral rewards and successfully edged and denied her sub under her guidance. I was emailed a wonderful thank you from mistress Y an hour later thanking me for subby's services. A small while after I was chatting about this with a close online friend of ours and she requested subby for one of her regular servicings. I sent him straight back out and he ate her pussy while we chatted on cam. This is a regular thing but if he satisfies her he still earns reward points. I felt on a roll so while he was still busy I contacted a couple we sometimes play with and asked if he would be welcome for some cuckold training today. They where bored so I sent him straight around from my friends. They where very quiet after his arrival and I was worried. Instead they had good news, for the first time subby not only licked her clit while she was fucked but ate and swallowed her creampie. He still hasn't sucked cock but I'm still very proud of this big step. He will be sucking cock for my viewing pleasure soon. So now subby has driven 120 miles today and is now sat in a motorway service station with a sore mouth and swollen blue balls waiting. Having so many tasks today has teased him to near bursting more than he has been for some time. I may give him permission to return and rest, or I might send him on more assignments. What do you beautiful people think I should do?