I’m getting a puppy at the end of July, so I’ve been putting a lot of thought into my training plan.
I think you’re on the right track with keeping the bun gated off at first and only doing introductions when the puppy is tired. If you’re getting an 8 week old, I would start introductions immediately, then maybe pull back as the puppy gets bigger and more exciteable. 8 week old puppies are just babies and are going to be interested in getting along with everyone. The older they get, the more rambunctious and playful they are, so you might need to limit interaction as the puppy gets bigger. I definitely wouldn’t wait to do the initial introduction though because the 8-12 week period is a good time for that – it’s the end of a puppy’s very very key socialization period, so whatever he’s introduced to at this age will stick with him. For an older dog I agree with waiting until he’s totally under control before doing intros, but a puppy that young should be introduced right away. A young pup on a leash and harness will be easy to control and you could start with the bunny behind a gate, then work up to puppy held on your lap with the bunny free to approach. Whether or not you let the puppy off your lap is a judgement call and depends on how the pup is doing, but I’d definitely leave the leash on for a long time.
Kikopup has a fantastic YouTube channel with dog training videos, so definitely check that out, especially if you’re new to dog training. The first things to work on with any pup is impulse control, like leave it. Teach him to be polite and wait for things he wants and it will be infinitely easier to introduce to the bun.