HHS doesn't know what time HealthCare.gov will open Tomorrow's the big day - open enrollment starts again for Obamacare health insurance plans. But maybe just don't wait up all night Friday if you're hoping to buy something. HealthCare.gov, the federal enrollment portal serving 30-plus states, opens on Saturday. However, the agency overseeing the health insurance marketplaces says it does not yet know exactly what time people can actually go online and purchase plans. Before the system goes live, technical staff plan one more overnight update to the computer system, and it's not clear how long it will take, according to a spokesman for the Centers for Medicare and Medicaid Services, the agency running the marketplaces. Once the update is done, people will be able to actually shop for plans - probably sometime early Saturday morning. Meanwhile, some other states running their own marketplaces have announced their own opening times. For example, the Web site for the Massachusetts Health Connector is supposed to be open for business at 8 a.m. You can still go onto HealthCare.gov right now to browse health plans, and you'll have three months to actually buy a health plan. But if you want coverage starting Jan. 1, you'd better get your selection in by Dec. 15. Maybe just don't wait up until midnight tonight to be the first person in line on HealthCare.gov.