I'm glad to hear your GMAT focus edition exam went well and that the process went smoothly. Receiving a notification that your score is under a 20-day check is not uncommon, as the GMAT scoring process can sometimes take a bit of time.
Many test-takers have reported experiencing a similar situation where their scores were under review for a period of time before being officially released. This is typically just part of the standard scoring process and doesn't necessarily indicate any issues with your exam.
In terms of how long it takes to receive the official scorecard after the 20-day check notification, the timeline can vary. I've seen reports from others who received their scores anywhere from a few days up to the full 20 days after getting the initial notification.
The important thing is not to worry too much during this review period. The GMAC is simply ensuring the integrity of the scoring process. As long as you know you put in a solid effort on test day, you should receive your official score soon.
I hope this helps provide some context and reassurance around the 20-day check notification you received. Best of luck, and I'm sure your hard work will pay off with a great GMAT score!