You have some time. First, educate yourself on the pros and cons of condo ownership vs. single family home. If you have or plan to start a family a single with a back yard and room to expand may be a better long term investment. Second, put money aside every month to save towards your down payment. Just because mortgage guidelines say you qualify for a mortgage does not mean that you will be comfortable paying that mortgage. Third, be realistic with your budget. Make sure that you factor in all possible monthly costs that you will have as a home owner.
That's not to say a 20% down payment is necessary. You can get an FHA loan with as little as 3.5% down.
I'd recommend speaking with a lender now to pull your credit report and identify any areas for improvement in the next 12-24 months. Like I said, the higher the credit the lower the interest rate you will qualify for.
I recommend only putting down as much as you can comfortably afford. Don't make yourself cash poor though. Remember you will still need money for paint, furniture, appliances, etc once you move in. If you use up all your cash and then have to open up credit cards at Home Depot and Best Buy then you're just robbing Peter to pay Paul as they say.
Hope this helps!
RE/MAX NE Ohio