Is this your first time using spd’s?
When I got my first set, I fitted them & spent ages riding round & round the grassy bit at the end of my road clipping in/out/in/out. I clipped out & back in while going quite fast & very slow. I practiced coming to a halt & clipping out. It all went well.
Feeling pleased with myself, I pedalled the 50yds or so back to the house, came to a halt…….and forgot to clip out!! Cue grabbing the window sill as I went down & being perched at about 45 degrees, unable to pull myself back up. In the end I had to face the fact that I was going to have to let myself drop.
It’s those moments when you aren’t thinking about it that will get you to start with, like coasting up to a set of traffic lights! Good luck!
Oh, and back the spring tension right off to start with.