Peter V. Lee, the head of the state's health insurance exchange, said the pace of registration has quickened as customers face a series of deadlines.
Roughly 15,000 consumers a day were signing up for coverage the first two days of last week.
"We are seeing huge interest," Lee said in a conference call with reporters Wednesday, adding that more people were becoming familiar with Covered California.
Customers who want their coverage for doctors' appointments and prescription drugs to start next month must select plans by Monday and pay their first premium by Jan. 6. The next enrollment deadline is Jan. 15 for coverage to begin Feb. 1. For those customers, a payment is due Jan. 28.
The first open enrollment period runs through March 31.
Lee likened the progress thus far to being in the first inning of a nine-inning game. He noted some trends to emerge since the exchange launched for business Oct. 1.
While some 55 percent of enrollees complete the process in one day, creating an account and selecting their plans, that still means about 45 percent of the applicants take longer, he said.
About 75 percent take a full week to come on board.
Covered California also is seeing major differences in the plans chosen by people with federal premium assistance versus those who pay full freight. About two-thirds of the customers with subsidies select a silver plan and 18 percent pick a bronze plan.
For those without subsidies, the breakdown is evenly spread across bronze, silver, gold and platinum. Higher-valued metals correspond with the higher the percentage of expenses paid for by the plans.
"They want to buy what they think is the best deal for them," Lee said.
PHOTO: Kristy Farrington, a student at Sacramento State University, looks at a pamphlet with information on Covered California on Oct. 16, 2013.