The slide is harder than heck and polish from the get go won't do more than a deep clean.
Do as you said and progress through the paper. That will get you a real smooth near mirror finish. Then go to the buffer wheel or the polish if you don't have a buffer.
I've started my PM45. I just take it a bit at a time. I got it shiny but no where near mirror finish. Did about the same on my K40.
Takes some effort and time but it's doable.
In Memory of Paul "Dietrich" Stines.
Dad: Say something nice to your cousin Shirley
Dietrich: For a fat girl you sure don't sweat much.
Cue sound of Head slap.
RIP Muggsy & TMan
"If you are a warrior legally authorized to carry a weapon and you step outside without that weapon, then you become a sheep, pretending that JOCKO will not come today."