I wouldn't worry about him going too low tonight....if anything, he may be even higher by morning, but there's nothing you can do but wait for the bounce to clear
Unfortunately, the answer is ECID - every cat is different! Looking at Gizzy's spreadsheet, I'd guess he'll clear it reasonably slowly. But then, who expected that 48 last night? My guess is you can go to bed without worry tonight and he'll be on his way down in the morning.