Timeframe to See A Real Improvement in a Credit Score

I have had past debt problems, including 5 charge-offs, a repossession and one judgement. I have worked very hard to pay all "bad debt" in full...I have never accepted a settlement. It has been approximately 3 years now and I have two remaining "bad debts" that total just under $2000. I have made payment arrangements with the collection agencies (these are both chargedoff debts) and will have both paid in full by the end of September.

In addition to paying off the debts, I have refrained from applying for loans, credit cards, etc. to keep the number of inquiries low on my credit reports. A year ago, my score was 540...which truly made me sick to my stomach. I could not get any kind of credit. In the past couple of months, I have managed to get a Verizon cell phone account and refinance my existing auto loan at a slighly lower percentage rate.

Now my question is, once those final two debts are paid, will I see an improvement in my score? I have kept all other accounts current and have two open credit card accounts. The others include my auto loan and student loans.

Will continuing to pay on these improve my score or should I be doing something else? Next year, I am planning to relocate and purchase a home on my own. I want my credit rating to be good enough that I can do this without relying on co-signers or an extremely high interest rate.