When the ball on the cylinder bolt (that's the part of the bolt that sticks up through the frame and engages the notch(s) in the cylinder) does this and locks the cylinder so it can't turn, the hammer will stop moving. If this happens before the tip on the trigger drops into the full-cock notch you will be unable to keep the hammer cocked - for obvious reasons.
If the hammer reaches the full cock position and the trigger drops into place while the bolt has not locked the cylinder the hammer can be rotated further backwards until the bolt either locks the cylinder or the hammer hits the backstrap. This is by far the most common situation you will encounter in Italian replicas.
In a perfect world (that is seldom seen but can happen) the bolt will be released about 1/8" short of the cylinder notch and as the cylinder rotates further the hammer will at approximately the same time.
1. Hit the backstrap.
2. The trigger's tip will drop into the full-cock notch
3. The bolt will align with a notch in the cylinder and lock it.
I should also explain that this was accomplished at a time when cap & ball Colt's had a mainspring that could do double duty in a pickup truck's suspension! Today some shooters lighten that spring, and when so doing the bolt should be timed for an earlier release - about 3/16" to 1/4" before lock-up. Otherwise the bolt may "jump the notch," and pass over it, leaving the cylinder unlocked.
At the other end of the cycle, you want the cylinder to start turning as soon as possible. Otherwise as the hammer rotates backwards there is a greater chance of cap fragments dropping down in the frame's hammer slot and jamming the action.
On the matter of "clicks," the Single Action Army model of 1873 has a quarter-cock or safety notch on the hammer's face so that you will get under ideal conditions, 4 (sort of) clicks.
1. The trigger comes to the quarter-cock notch and passes it.
2. The trigger comes to the half-cock notch and passes it.
3. The cylinder bolt is released.
4. The trigger engages the full-cock notch.
But Colt's cap & ball revolvers did not have a quarter-cock notch on the hammer, so you are unlikely to get 4 clicks.