That's strictly against the gpl. If you aren't providing the source code, you must provide an offer to all third parties. Anybody then who receives the binary, from you or from others, has a right to receive the source code from you for no more than the cost of the digital distribution. This must be provided for the first three years. This begins the moment you distribute a binary to anyone but yourself.
You aren't the first person on this forum to falsely believe you can provide the source code whenever you want. But it begins when you distribute the first binary, as the written offer must accompany it.
If you'd rather do your own work and release things on your own schedule, then don't use already licensed projects that require you to release the source earlier. Or don't release the binary to anybody. You can use it for your own private use. But as soon as you give somebody else the binary, you are obligated to offer them the source for three years.
Complain all you want. That's the language of the license of the project you're using.
I have no idea why this thread is still alive and not locked. You are very obviously violating the original license if you're distributing the modified work to anybody, without an offer for the source code.
Oh, and if somebody gets the binary from you and then that person sends the binary to somebody else, that somebody else also has the right to receive the source code from you upon request.
