On-time payments indirectly lead to score increases due to the increase in the age of the accounts, and thus improvement in average age of accounts and date of oldest credit line, and based on increasing the age of the prior delinquencies. It is indirect.
A few months aging does not produce significant score increases in age of accounts and aging of derogs. You are probably correct in your premise that it will take a year to show significant score increase based on those factors.
The more significant increase may come from inquiries becoming more than a year of age, after which they are no longer scored, and new accounts becoming more than a year of age. Those are New Credit scoring factors.
I concur that two revolving will help in the scoring of util of revolving credit, as FICO puts heavy weight on the showing of effective use of discretionary, revolving credit.
However, addition of new accounts is not a sure short-term score boost. Again, it will take about a year to reap benefit, as establishing the new accounts will require inquiries in the application process, which will be scored for a year, will add a new TL under one year, and will reduce the average age of accounts. It's a longer-term rebuilding effort as opposed to a quick score fix.
Short-term improvement would, in his situation, most likely result from deletion of prior derogs. Payment history is the highest-weighted scoring category, and if the derogs are under approx two years, their deletion would most likely give the greatest short-term score boost. Additionally, apart from the FICO score issue, it will make his credit report look better when a mortgage lendor does the inevitable manual review of his credit history.
I would concentrate on sending GW letters.
