You're jumping from first date to blowjob to boyfriend. Slow it down and keep it simple.
You're both adults. Just relax and have a good time. If the opportunity arises and you're both "clicking" then let things happen on their own.
A first date is hardly to time to be thinking exclusivity or not.
There are sooo many things that you have to keep in mind. Firstly, you don't know what HIS sexual history is so even if it's a BJ, make sure he's all wrapped up. Until you can be 100% certain about that you owe it to yourself to protect yourself.
DON'T let your horniness lead you to recklessness.