I have an SSL certificate that expires on Februray 15, 2015. What if I install new certificate on my server on Feb 10, 2015. Will my certificate work with new renewed certificate on Feb 10 as my old certificate expires on Feb 15?
What kind of server is it? A web server? If you install the new certificate, it should work. When a certificate is signed, it is available to use right away. Clients connecting to the server will authenticate the certificate as long as they have the signing authority certificate installed as a trusted CA (i.e. it was signed by a certified signing authority, who you presumably bought the new certificate from).