SMH
If you read the paper that comes with all XS Power the first thing it tells you in bold italic letters is Proper Charging is Crucial! Charge before initial use!
It also even states this in the instruction manuals on the site.
http://www.4xspower.com/Dseries-Instructions.pdf
As for any new battery no matter what manufacture, or what type it is, or where you bought it you should give it a full charge before use.
You have no idea how long that new battery has sat on a shelf at said store or warehouse and this is why you should always give it a full charge.