This week, Google began rolling out its dreaded mobile-friendly update. It’s unclear exactly how long it will take for the roll-out to complete, but it sounds like it will be at least a full week, based on what Google has said.

The company did indicate that it has rolled out completely in at least some of its data centers.

“So that is something where I think you will probably see that change over the course of a week, maybe a week and a half – something like that,” said Google’s John Mueller in a webmaster hangout. “From the first day to the next day, I don’t think you’ll see a big change. But if you compare last week to next week, then you should see a big change.”

While it’s still early to know what kinds of businesses are going to be impacted most, it does appear that law sites might get hit pretty hard.

Of course it’s not like the update is targeting any particular vertical, but law firm search engine Lawyer.com says it has reviewed mobile readiness across its database of over 100,000 U.S. law firm sites using Google’s mobile-friendly test on April 21, and found that 46% of solo firms failed Google’s requirements. Larger firms did a bit better with a 33% failure rate. The site says:

Websites for Texas-based law firms passed Google’s tests 68% of the time compared to only 65% for California-based law firms and 61% for both New York and Florida-based firms. Male owned solo firms passed slightly more often than female owned solo firms with rates of 60% and 58%, respectively. Websites of solo lawyers 50 years or older had a 54% pass rate while sites of younger solo lawyers reached 55%. Personal Injury law firms had the highest pass rate of all major practice areas (67%), while Real Estate firms had a low pass rate at only 57%. Patent law firms, which often have tech savvy partners, surprisingly had a low pass rate of just 44%.

Home pages of three of the top-five grossing law firms in the U.S. failed Google’s mobile-friendly test; Latham & Watkins, Skadden Arps, and Clifford Chance all have websites that can expect organic search traffic declines until adding responsive design elements. Google has indicated that drops in traffic will not be reflected immediately and may take over a week for indexing to occur.

“Making the necessary adjustments is extremely important for business websites in any industry,” said Lawyer.com CEO Gerald Gorman. “It is especially important in the legal services industry as most users now start their Lawyer search on Google using a mobile phone or tablet.”

SEO Clarity is keeping score on what’s happening with the update here. On the third day of the roll-out, it reported that out of 50,000 keywords it analyzed and the associated 60,000 domains appearing in the Top 10 results in Google’s desktop and mobile SERPs, that day showed a 0.5% change in the opposite direction.

Image via Google