When filing an H1b transfer [assuming your first employer did not withdraw your H1b], you may have as long as 60 days to file the new application. So a pay slip two weeks old will not be an issue. Be sure to discuss it with your attorney.
The above is intended only as general information, and does not constitute legal advice. You must speak with an attorney to discuss your individual case.
You have to show you are in a valid non-immigrant status when the I-129 is filed.
The information contained in this answer is provided for informational purposes only, and should not be construed as legal advice on any subject matter,not should it be viewed as establishing an attorney client relationship of any kind.