If you have multiple staterooms, you have to do them one at a time. You can do it from one log in, just switch reservations.
Preparation:
1. have downloaded to your device 1) a clean headshot of each person (straight on, no sunglasses, hats or hair accessories, shoulders included, cannot be the same as passport photo), low resolution and 2) passport photo. You do not need the signature page of the passport, but make sure your photo has all the edges of the main page, including the string of information on the very bottom.
DCL uses this to digitally input the information into the checkin—if they can’t read it, you have to manually type it in which will slow you down and you risk them rejecting the photo on review.
Jpeg/Jpg file types work best.
2. a document with each passenger's birthdate, address, cell phone, email address, passport number, passport expiration, safe word for kids club, emergency contact name, emergency contact phone number, credit card information
3. Flight information for all legs -- date, airline, airport from, airport to, confirmation number/record locator number, flight number, time departure, time arrival
For speed:
1. Upload photo and if it says it doesn't meet the criteria, click SAVE and move on. Deal with it after you get your PAT.
2. For Onboard account, select Cash to get through it quickly
3. For Travel Plans, select Driving to get through it quickly. I just used home address for the return.
4. Finish each stateroom then go back and fix photo, add credit card, add flight information.
You can change PAT times, so keep checking to see if any better ones become available closer to the cruise.
You can edit the Online Checkin information as much as you want (at least I have so far), until that piece of it goes under review and can't be modified.
ETA: Make sure everyone has at least six months remaining on passport at the time of the trip. If not, check in and get the passport(s) renewed and update to the new one. If you are not from the US, be sure to research any VISA requirements.
ETA: You must have original birth certificates to board now, not copies.