The whole trial is a sham. I'm sick and tired of hearing "34 counts...". That is based on 34 installment payments, where checks were written out 34 times to cover the one large sum of "hush" money. So it isn't 34 things to convict him on, it's about one single thing.
And... the 34 payments were begun when Donald Trump was President in the White House, so the immunity does indeed carry because he was President when the so-called illegal payments began.
There should have been no conviction at all, innocent or guilty. And I believe Trump to be innocent, despite the 4-4-4 juror ruling (only a fraction of the juror pool convicted him). The trial was indeed a sham.
I don't like it, but I'm pretty sure that's how it'll shake out.