Hi Emily,
Now that he is home, contact him and start a normal conversation.
You can talk about his trip, how he is settling in, etc.
There is a good chance that during the course of the conversation, he will ask about the date.
If he doesn’t, you should bring it up towards the end of the conversation.
It is best not to appear overzealous.
So, just wait it out until towards the end of the conversation to remind him about the plans for a date, if he hasn’t brought it up already.
Being that you are the one who asked him out first and initiated everything, it wouldn’t be inappropriate to do this.