Gents,
You may be aware of the timing chain issues with *** petrol engines in anything from Audi 4.2 V8 to Polo 1.2. Chains or tensioners have been failing from as early as 40k miles, resulting in the need for a new engine, even though according to *** they never need replacing. Aside from the emissions scandal, *** are obviously a highly reputable company and deny there are any underlying design/manufacturing/quality issues with their chains and tensioners! How do I know? Wife's 60k miles Golf started to make a brief rattle sound on stone cold start-up, which could only be heard with door open and/or bonnet up. Turns out chain was on its last legs and so engine (and car) was on its way to being written off.
Given the beast under the Maserati's bonnet is a rather highly tuned piece of Italian engineering, I personally would be inclined to follow the Manufacturer's guidelines and wonder if waiting to hear a slapping chain means some harm would already have been done to the engine?