my 7 and a half old week staffy has now got a collar, when would it be the best age for me to introduce him to a lead? as i've been advised the younger the better??

Firstly start by attaching the lead to his collar when hes eating his meal. he will learn to associate the lead with good things. Dont pull or tug him at all at this point. As he gets used to this you can attach the lead when he has a treat or a play toy. Next gently hold the lead whilst he is eating or playing with a toy. Encourage him to follow you while you hold the lead ( do not pull) keep it loose walk backwards calling him with a toy. Hewill soon start to learn that the lead is a nice thing and not a bad thing. You can gradually build it up to where you are gently leading him in a certain direction putting a little more tension against him when he feels comfortable. Do it slowly and make it a pleasant association and youll have your new little puppy walking on a lead in no time. Never drag a puppy by a lead. Build it up and by the time you hit the big wide world together he will not fear the lead, but remember he will be fearful of alot of things in the big scary outside world. Take your time with him and encourage him rather than forcing.
Happy puppy days :):):)
Jodi