I am planning on hosting a web app on Google App Engine. I am planning on buying the domain from GoDaddy. Will I have to wait 3 months before I can transfer the domain from GoDaddy to GAE (or at least change the DNS settings to point to the GAE severs)?
Most domain registrars require you to wait a specified period of time between transfers (usually 60-90 days) for various reasons, including fraud. I don't know about GoDaddy in terms of whether they will allow you to trasnfer the DNS, but Namecheap will get your domain registered for you and allow you to transfer the DNS right away (you still have to wait the 60 days before you can transfer the domain to a different registrar though.)
From the GoDaddy Support Docs:
NOTE: A 60-day transfer restriction period applies when you register or transfer a domain name, update the registrant contact's organization, or update the registrant contact's first or last name and an organization is not listed. For more information, see ICANN's Policy on Transfer of Registrations Between Registrars and our Domain Name Change of Registrant Agreement.
So, there you have it, there is a 60-day restriction. But they are simply enforcing the rules set by ICANN.
(or at least change the DNS settings to point to the GAE severs)
However, I can't believe there is any such restriction (with any registrar) on simply changing the DNS. Some registrars might charge you for this service, but I don't believe GoDaddy does since you can do this yourself via the control panel. Changing the DNS is usually the first thing you want to do after registering a domain, so it would be insane to pose a time restriction on this.