Lithium
batteries are best when stored with a full charge. So
batteries come from the factory with a charge. Sitting around not to mention time spent being shipped from here to there and then to you will mean the batteries arrive with less than a full charge. If its the only battery for a new mod go ahead and use them, enjoy your new mod for a bit. But they most likely will need to be charged soon.
Generally I'll charge them before I use them.