By reading xp bar at start of your script, you can get pretty accurate progress reports.

Simba Code:
startingxp:=getXPBarAmount;

For example:

Simba Code:
currentxp:=getXPBarAmount;
xP:=round((currentxp-startingxp)/itemxp);
itemshr := Round((xp)/ (GetTimeRunning / 3600000.0));

itemxp is the amount exp you get for one time created.

For example, you make bows, you input there xp for one bow created.