The only access for days on market that I know is through the MLS (agent side). I would suggest to start receiving properties right to your email directly from MLS. This is the core of where all listings start on the internet and you would be able to get the latest, most up-to-date listing information. If you would like to have this service, you can email me with your information.
Here is a link about the tax credit for first-time home buyers.
Happy House Hunting!
Shri Mapes the CIncy House Expert
Keep in mind though, that it is often difficult to surmise the "true" days on market figure, as sometimes the history will only include the most recent listing timeframe and not show expired listing term lengths. In the current market, it could extend days on market by anywhere from 180 to 360 days.