What to do when shaking begins?

Hello guys, after years of thinking about whether to try massage or not, I decided to buy the equipment and give it a shot. I’ve read a lot of guides on Reddit and here, but I want to clarify one thing. I feel a lot of pleasure and produce a lot of milk, but I’m not really sure how to react when the body shaking starts. What I mean is that at that moment I automatically tighten and hold the massager, but when I relax, the shaking stops; when I tighten again, it intensifies. So my question is: when the body shaking begins, should I keep holding the Aneros, or is it better to maintain continuous stimulation by tightening and relaxing the PC muscles?

Overall, I already feel a lot of pleasure and relaxation, but any tips on how to go further are welcome. Thank you for your answers and best regards.