Technically, the length of employment is not factored into your score. What most people don't realize is that it can affect your chance for approval on a loan. I've recently been denied because of length of employment. (3 months, like yourself) Typically most lenders want to see one year or more with your current employer.
Taken with a grain of salt, there are a few other factors. If your credit score is high enough, they are likely to ignore employment history. If it's (your CR) in the fair range, it's more of a gray area. It just depends on their underwriting standards. If your current length of employment is under 1 year, to 6 months, they also pay attention to job type. If it's a complete career change they will likely deny the application.
I would suggest saving up your money for the next few months for a larger down payment and then apply when you've been on the job for 6 months. If you have checked your FICOs, have a "good" score, you should be able to get approved. If you're in the "fair" or lower, I wouldn't risk lowering it with an inquiry and a denial. In both cases, waiting 6 months would probably be ideal.
