I speak for RB211, as I am used to working on these. There is an asterisk on the fan hub where the N°1 blade goes. Then you number them in an anti clockwise direction when looking aft into the engine. Most of the time tere is an arrow next to the asterisk going ACW. The numbering is done before blade removal, so it will only stay the same when no blades are replaced (e.g. dirt removal of blade, lubrication, attrition liner repair...). When blades are replaced, engineers make a new distribution according to moment weights and they will have a paper like "blade 1 fits place 1; blade 2 fits place 3: blade 3 fits place 33,...
So as a pilot, ignore blade numbering.
Btw, numbering fan blades with an alcohol marker is a bad habit I often see. Not good on titanium blades. Better put painters tape on the blade and write on that.
As for your question, once a blade has been blended, it is seen as a serviceable one without limits. If there are limits, the blade will not be on that engine for long ( 1 or 2 flights). Any new dings will create a new situation which has to be looked up in the AMM. This manual states limits for multiple dings on one blade.
Swedish Steve, I had some similar incident. We got a wrong blade distribution faxed. When starting the engine afterwards for the check it was like the wing fell off with a very loud grinding noise, without even fully spooling up. Shutted down the engine and recalled the eicas page showing 5.9 units of vibration!
