DH had it done within six months of number 2 - we knew two was it for us so was easy decision but we are mid 30's. If we had been 10 years younger I would have been against it because I have got relatives and worked with many men who had it done only to then end up no longer being with the partner they made that decision with and having a new partner and wanting something different. You don't mention whether there are any reasons you don't want to use other contraceptive methods - those reasons would come into a decision for me. In your shoes I would park the decision a couple of years and review - if both still want and not wavering after two years then would go ahead. I do also think stage in relationship comes into it, not just age and would also prob say to someone mid 30's only in a relationship for a couple of years to perhaps think about it a little longer.