Perfectly normal.
Timing refers to the sequence of the cylinder's unlocking, rotating, and re-locking.
With the Colt and "clones" the timing sequence is:
As the hammer starts back, the bolt drops out of engagement with the cylinder BEFORE the cylinder starts to rotate.
The bolt drops back onto the cylinder at some point before it's too close to the locking notch.
The bolt drops into the locking notch and locks the cylinder BEFORE the hammer is fully cocked.
Since I was mostly a Colt double action 'smith, I'm not well-up on the actual timing of the SAA, so just were the bolt is supposed to drop back onto the cylinder I just don't remember.
As for the cylinder having "back-lash" as the hammer is cocked, this is normal and a sign that the cylinder is free to rotate properly. A tight or binding cylinder won't do this, and is often a sign of a possible problem.