It's time to sign up or shut up.

Bidder registration for

Google's

initial public offering will close at 5 p.m. Eastern Daylight Time on Thursday, the company said.

"The auction for shares of Google's Class A common stock will commence soon thereafter," the search engine company said Tuesday in a message posted on its IPO Web site

ipo.google.com.

The posting suggests Google's IPO could begin as soon as late this week, which is earlier than Wall Street had come to expect. Recent talk was that a number of technical glitches, and possibly a weak IPO market, would keep the offering on the shelf till the week of Aug. 16.

The news comes just a day after Google settled a pair of nagging disagreements with big rival and longtime investor

Yahoo!

(YHOO)

. Google will issue some $300 million in stock to Yahoo! to close out the patent and warrant disputes.

As part of Monday's agreement, Yahoo! is tripling the number of shares it plans to sell in Google's IPO, to 1.6 million. Yahoo!'s move will have the effect of increasing the size of the offering to 25.7 million shares from 24.6 million, though the proceeds to Google won't be changed.

The news comes as Wall Street, dealing with its annual August dog days, fills a news vacuum with rumblings that Google's IPO is facing weak demand and will have to be made more attractive to supposedly value-obsessed investors.

The company has shown remarkable growth in recent years based on the success of its pay-per-click search engine advertising business, but investors have grumbled about about Google's stinginess in public discussions of its business prospects, a capital structure giving its co-founders unassailable voting control, and the richness of the proposed price range for the company's stock.

Whether this commentary will lead to an offering price below the proposed $108-$135 price range, or whether it is simply trash talk that will be obliterated by big-spending bidders, remains to be seen. Injecting uncertainty into the whole affair is the expected bigger-than-usual participation, as far as IPOs are concerned, of retail investors in Google's auction.

In any case, the company's arrival will mean more competition for rivals ranging from Yahoo! and

Microsoft

(MSFT) - Get Report

to

Ask Jeeves

(ASKJ)

and

Mamma.com

(MAMA)

.

To participate in Google's Dutch auction of its shares, investors will need a bidder ID, obtained in the registration process. They'll also need an account at one of the brokerages that is underwriting the IPO, and will have to meet that firm's particular qualifications for bidding on Google shares.

By permitting investors to submit bids for as few as five shares in its offering, Google has lowered a usual investment hurdle; on the other hand, the company has raised that hurdle with a share count that puts the expected per-share price more than 5 times the usual figure for an IPO.

While professionals are accustomed to thinking of retail investors as less disciplined than they, it wasn't just individual investors who lost money in the turn-of-the-century dot-com boom.