The way I check my spokes is easy and only takes a minute .. I take a screwdriver and gently tap each spoke. They will ping ..the ping will be similar on all of all the spokes.If I come across one that is loose it will sound different...deeper.. if this is the case take I take my spoke tool and tighten it till it sounds the same
I do agree with people in this thread though that a new bike should not have had this issue and if too many spokes are loose a dealer needs to set them to make sure the rim is true.