Dealer stickers should come off first day you bring your new car home. Emblem or badges I would use dental floss with hair dryer blown on the emblem to soften up the adhesives. Basically floss the emblem off. Debadging a car makes the car look clean by removing all the nonsense branding and model trim names.
I have done the same thing with all my cars. Day 1: Pull the damn badges off! haha. The 2019/2020 Forester looks so much cleaner without the badges because there are already so many lines. Love the look!
Why are you even accepting a car with dealer stickers/ads? I make them add a clause in the sales agreement to remove all dealer badges/stickers/ad-crap. When taking delivery, I make sure they are removed.
Only once, 14 years ago, I had to threaten a dealership that I was ready to walk-away if they don't comply -- they eventually agreed to it. Most dealership employees don't care one way or the other.