We get one each year for one of our party (ASD) so we go for rope drop on the first day and rush into Guest Relations. As we are one of the first to arrive it doesn't take long, the qualifying person needs to be with you though as they have to take a photo using an iPad. The whole process should only take 5-10 minutes, your other party members could go into the shops to pass the time or just admire and savour their surroundings. I am sure they will understand.
Since they started linking the
DAS electronically to the Magicband or ticket, you will need the person the DAS is being requested for, their Magicband or ticket PLUS the Magicbands or tickets of the other members of your group that you want linked to the DASholder.
The CM at Guest Relations will ask a few questions about the person's needs. If they qualify for DAS, a picture of the person will be taken with an iPad and DAS will be entered onto their Magicband or park ticket.
Then, other members of your group will have their Magicbands or tickets linked to the DAS holder's. They don't necessarily need to be there, but you will need their Magicbands/tickets, so most people find it easier to just have the people present. It's also possible you may be asked to have the rest of the party present - some people have reported the Magicbands were enough and others were asked to have the other members present.
It's VERY unlikely that a whole group of 20 will be linked - the usual number for DAS is no more than 6 (5 plus the person with a disability). So, you will need to decide which people will be linked.
You can always ask for the whole group, just be aware you will likely be told no.
No matter how many are linked, there will be times when you need to divide into smaller groups of no more then 6. This is usually because of seating.
You can find more information in the WDW DAS thread locked near the top of this board. Only the first post in that thread is kept up to date. The rest is from just before and just after DAS was started.