Of course there's going to be interim managers. No point putting a time frame on it because it'll take as long as it does to find the new coach.
I would place money on Rudan being the manager by Wednesday.
Anyway, judging Ernie's 3 seasons - he was well liked off the pitch and did terrific work to bring the club to a new level of professionalism; but on the pitch, the teams he has put out have been largely disappointing.