Communicate clearly at the beginning of your project.
Identify each other's roles
Be as specific as possible. If you want your PM to help you set priorities, weigh in on features, anything at all, say so. If you want them to help you organize your time in a way that is the most effective for your productivity, let them know. Identify everything that will need to be taken care of over the course of the project, and assign those responsibilities to each other. As new responsibilities reveal themselves, don't assume that a person is going to take care of it - address it and assign it to an individual.
Kick off your project with a cheesy workshop
Hang out for a few hours and do some team building exercises. Get to know each other better. It really helps.
Communicate your strengths and weaknesses
Don't be afraid to let each other know what you suck at. I'm bad at managing lists of priorities and I love a PM who keeps that list running for me. So I let them know that. I also really hate meetings and standups, and it's good for my PM to know that, even if we still have to do them, they'll know why I'm a little grumpy.
Be honest about productivity tool preference
If you love trello and hate asana, bring it up at the beginning. Everyone's goal should be to make the work great, in the most efficient way possible. Find ways to compromise on these little things and it will be less painful for everyone.
Once you've communicated everything at the beginning, there should be a process in place for you to work easily together. Standups every morning, design reviews every other day, a channel for communication on slack, expectations on the "headphone rule", etc. If you've gotten all of these things out of the way in the very beginning, it should be easy for the designers to find many uninterrupted hours of heads-down, deep-work time. At this point the PM should be aware of what they're working on, everyone knows what to expect next, and there should be minimal surprises. It's all about the product, and room for Deep Work is key!