He was convicted for falsifying business records nothing else. All the records that were fraudulently submitted were starting Jan 2017.

The hush money payment wasn't illegal, hiding it was.

It rose to a felony instead of misdemeanor because it was done in service another crime which is campaign finance violation, the other crime need not be proven and he was not charged with that.

All they got him for paying cohen illegally.

Also there was some evidence introduced from his time as president , he would argue that evidence is now inadmissible and in a favourable court they will declare mistrial and ask the lower court to do it again.

If he wins again the prosecution will have to pause and he gets the delay he wants.