I think the best he can hope for as a result of his appeal is a slight reduction in sentence.
Clamoring to stay out of jail just makes him appear to be unwilling to accept responsibility for his actions.
If I was him, I’d insist on immediately starting to serve my sentence. That projects the appearance of accepting responsibility, and it opens up the possibility of a sympathetic judge reducing his sentence to “time served” when the appeal is heard, even if it’s only been a few months.
I can envision it now: “This court can see that Mr. McDonnell is contrite and has accepted responsibility for his actions. On his own accord, he dutifully reported to prison to begin his sentence. During his incarceration he has been a model prisoner. He and his family have suffered greatly. Human compassion, and even our own State Constitution implore us to temper our justice with mercy, and I see no reason why this honorable yet flawed man should not receive the benefit of that mercy... ...etc. etc.”
It appears the Court of Appeals believes the conviction might be overturned. The entire case was highly controversial, and some might say, politically motivated. Why, under those circumstances, would he spend a day in prison?