Time is flying by as the federal government attempts to implement the biggest changes to the American health-care system in half a century. Here are three important Obamacare deadlines that consumers need to mark on their calendars.

Nov. 30, 2013
Perhaps the most important date of all is Nov. 30. That's the deadline the Obama administration has given for fixing the multitude of problems plaguing the Healthcare.gov website used by 36 states.

Many consumers attempting to use the Obamacare website over the past six weeks have experienced frustration at the slowness of the site and with errors that prevented them from completing the application process. Insurance companies were also exasperated by the technical issues.

In an interview with CNBC, Aetna CEO Mark Bertolini vented his disappointment with the Obamacare online marketplace, saying, "There's so much wrong, you just don't know what's broken until you get a lot more of it fixed." Bertolini, however, wasn't really surprised by the problems. He indicated that Aetna employees became increasingly nervous as the Oct. 1 implementation date approached, noting multiple missed deadlines the federal government missed leading up to the launch.

Health and Human Services Secretary Kathleen Sebelius said this week that there were a "couple of hundred" problems to fix with Healthcare.gov, but that the team charged with making the needed changes is making progress. Sebelius stated that the website could now handle around 17,000 applications per hour with few errors. However, not long afterward, a federal spokesperson reported more performance problems and errors. 

Dec. 15, 2013
Americans needing health insurance to go into effect by the beginning of 2014 must enroll by Dec. 15. Assuming that the Healthcare.gov website is working well by the end of November, that gives consumers two weeks to shop for insurance.

For those who have already gone through the application process on Healthcare.gov, you might want to follow up with the insurance company that you selected if you haven't received confirmation of your new policy by early December. Several insurers reported significant problems with the enrollment information received from the Obamacare health insurance exchange.

Even if you submitted a paper application, you probably want to check to make sure you're covered if you haven't heard from the insurance company. Those applications ultimately must be entered into the computer system that is still experiencing significant problems.

March 31, 2014
If you want to avoid facing a financial penalty from Obamacare's individual mandate, you need to sign up for insurance by March 31. This is a later date than what the letter of the law states.

The Affordable Care Act imposes a penalty if an individual who isn't otherwise exempt goes without health insurance for three or more months. Because the effective date of coverage is always at the first of the month and insurers need adequate time to process an application, that meant Americans needed to enroll by Feb. 15 to be covered on March 1 and avoid any penalties.

However, the health-reform legislation allows the Department of Health and Human Services, or HHS, to grant hardship exemptions in some cases. Using this provision, HHS created a hardship exemption for 2014 only that gives Americans another six weeks to enroll because of the website debacle. This special exemption pushed the Obamacare enrollment deadline out to March 31.

Deadlines dead on arrival?
If the Nov. 30 date for correcting the website issues joins the list of earlier missed deadlines that Aetna's Mark Bertolini cited, it's likely that none of the other current deadlines that affect consumers will matter. Without a properly functioning website, Obamacare won't roll out on schedule.

Sen. Jeanne Shaheen (D-N.H.) is pushing a bill that would extend the open enrollment period because of the serious technical issues. Others are calling for a delay of the individual mandate itself.

Humana Chief Operating Officer Jim Murray said his company now expects a delay. Murray told investors that "given where we're at today, our assumption is that there will be an extension to the open enrollment period."

Go ahead and mark the dates of Nov. 30, Dec. 15, and March 31 on your calendars -- but you might want to use a pencil rather than a pen. There's a reasonable chance that these Obamacare deadlines could be dead on arrival.