When is the proper time to file taxes for my new C Corporation?

Unfortunately you have to file your taxes for every year even if you do not have any business activity as well as to comply with your state fillings and the filings for your Secretary of State. You cannot add the activity of 2 years together, there has to be a filing for every year, in this case $0 revenue for 2015 but you still have to file it with $0

If you start a U.S. C corporation, you should file an annual Form 1120 income tax return each year. Under U.S. tax rules, every C corporation that conducts business should file a tax return, even if the corporation has no revenues, expenses or profits. It's also important to file income tax returns to preserve the net operating loss carry forwards. In the early stages of a company, you have mostly expenses which put the corporation into a net taxable loss position. Net operating losses are carried forward to subsequent tax years and can be used to offset future corporate profits. However, if you do not file corporate income taxes to report these losses, you will not be able to use them in future tax years, which could cost you a significant amount of income tax in the future. I highly recommend you consult with a qualified tax adviser to file the tax returns, as well as advise you on the deductability of certain expenses, and how you can plan to use tax losses in future years.