There is no SET # of pounds for a given octane, you can run as much as your car will allow, turn it up slowly till you see a lil bit of knock and turn it back down when you do.
22 psi no knock but running low on gas headed to the store for more 110 but if i do see knock after next turn or when ever can i just add c-16 instead of turning it back down im only putting 4gallons of 110 in at a time so i wont have to mix it with the higher octane stuff.
Ive run 27-28psi many times on 110 without any alky. Thee is no set number. CR, timing, cam profile and other things will effect the detonation threshold. Dont wait for a little detonaiton as suggested. If your in doubt go with more octane.