Can I give notice to my Employer?

Hi..Please help..I am looking to buy a property. Got my house offer accepted and lender survey completed. ie., mortgage process in place.
Now starts the story..I read on the internet that lenders would normally look for employment of 1 year or more. I am a permanent employee working with my current employer for 2 years. Now, I got an employment offer which is 15k more.

While my mortgage application is in process, and me on a 3 months employment notice period, Can I give notice to my employer. I have already received my new offer with +15k salary.

If it is risky, when is the best time to give the notice? After getting a mortgage offer?

Thanks,
confused