The sticker and the owners manual give a low value for chain slack. If you use this value make sure you measure it with the suspension compressed. If you don't have someone to help you can either stand on the right hand side of the bike and put your weight across the saddle then reach down to the chain, or, if you're not that kind of contortionist, you can use a bike tie down strap ( the kind with self gripping buckles ) wrapped round the wheel rim and the seat to compress the suspension.
It is easier with a paddock stand, which you also need to apply chain lube easily.
Too tight is generally more harmful than too loose. A tight chain will wear itself and the sprockets and will eventually damage the gearbox bearing and seal.