This is normal for most strains at this time of flowering....that is if it,s not a nute prob or something but if it's just normal yellowing,you can wash your hand real good then sterilize a rozor and cut them of after most of it turns yellow because it's using the nutes from that leaf before it dies.
Need some info to tell you if it's some other prob.
nute level,ph,ect...
Overwatering is more of a root rot thing...you can smell it from the bottom of your growing medium and the plant will ussually start growing sideways or fall over...lots of warning...I try and wait as long as possible to water,but still when ever they need it.