If they are reported on your Credit reports, showing responsible payment history always builds up your credit profile.
Since it is a student loan and an installment loan it will not help as much as revolving credit, but its a good part of a mix of credit.
DoFD= Date of First Delinquency – This is the date of the delinquency that led to the collection/charge off status. This is NOT the first time you were ever delinquent on the account. It is the last time you got behind on payments and never again got caught up. If you are looking at your EX or TU report, it may not show DoFD, instead it will say “This account scheduled to remain until XXXXX” or something to that affect, subtract 7-7.5 years from this date and you will have DoFD.
SOL= Statute of Limitations—this is state based and sets the time limit the creditors have to sue you to recover their money. Now, they can sue after this time expires, but you must show up in court and use “expired SOL” as your defense and you win. Never ignore a summons just because you are past SOL. If the creditor arrives in court and you fail to show then you will lose a default judgement.