A few thoughts. I would not put the fertilizer down before you seed, I would wait until the grass is up and running. In your climate I assume you would ideally need to split applications throughout the year unless you can get a very extended slow release (expensive).
You can get two different fertilizers, say something close to 25-0-0 and another for 0-0-20 or, as Lyn said, get something combined that is close enough.
Remember also that you can get something with half that analysis (say 12-0-10) and apply twice the recommended amount. Or, conversely, get something like 50-0-40 and apply half the recommended amount (if there is such a thing - just an example to explain the concept). What counts is the ratio and the amount applied rather than just the analysis.
If you go for something that is outside an easy division to get the ratio, you can calculate now much N (nitrogen) and K (potassium) you need to apply from the analysis they gave and the amount recommended. Was it clear that they meant 2.5 lbs of a fertilizer with that specified analysis, or did they mean 2.5 lbs of nitrogen per 1,000?
