The company's shares, which have fallen steadily since it announced in early September it would launch two iPhones within two months, rose nearly 3 percent in response.
Pre-orders for the much-anticipated 10th anniversary phone started from 12.01am PT (7:01 GMT) on Friday.
"We can see from the initial response, customer demand is off the charts," an Apple spokeswoman told Reuters.
"We're working hard to get this revolutionary new product into the hands of every customer who wants one, as quickly as possible."
The company's website showed delivery times pushed out to five to six weeks for the phone, compared to an initial plan of November 3.
IPhone X's launch follows weeks of concerns among analysts about the production of the new phone, which for the first time includes new facial identification software to replace the fingerprint used on previous phones.
Analysts have cautioned that production of the phone was below target, due to difficulties in producing the TrueDepth camera system, which houses sophisticated cameras and sensors making it possible to unlock the phone using Face ID.
Wireless carriers in the United States and Canada have reported slow third-quarter customer upgrades.
Major promotions on the iPhone X from US carriers have yet to materialise, and in some cases, the offers have been even less generous than what was available for the iPhone 8, said Walter Piecyk, an analyst at BTIG in a research note on Thursday. The base price for the phone is $999 (roughly Rs. 65,000).
He noted that Sprint Corp's iPhone X promotion of $350 in savings for trading in an eligible device was the most aggressive but still lower than what it offered for last year's launch of the iPhone 7.
However, electronics retailer Best Buy Co is charging shoppers an extra $100, if they wish to buy an unactivated iPhone X outright.
If customers order the phone on an instalment billing plan, they will pay the same price charged by Apple and the carriers.
"Our prices reflect the fact that no matter a customer's desired plan or carrier, or whether a customer is on a business or personal plan, they are able to get a phone the way they want at Best Buy," Best Buy spokeswoman Carly Charlson said.
"Our customers have told us they want this flexibility and sometimes that has a cost."
© Thomson Reuters 2017