Yes, I know its the standard answer to many questions!
My mate over tut road tiled his bathroom floor. Wise lad, he removed the WC & the pedestal under the basin first.
WC went back in OK, after I'd lent him a drill driver, multi material bit, plugs, screws & some LS-X. I'm like a piggin hire shop in our close.
Pedestal wouldn't fit back under the basin. He asked if he could borrow an angle grinder to trim it. Hmmmm.
Diamond blade, masking tape & he has cut 6mm off the base of the pedestal leaving a near perfect edge. Wouldn't have though it possible myself.
So now you know.
Q; How to I trim a porcelain pedestal? A; Angle grinder!