Fly direct into Phuket. Easier to stay in first hotel for six days if that works for you. Minimises all the paperwork etc. Thai weekend flights are direct
ask the hotel for a SHABA certificate. They are used to issuing them for the sandbox. It confirms you have booked and paid for room in approved hotel. I used it for my Pass
I did Thai Pass first and just said staying 28 days. My visa took 14 days. Arrived before I left luckily. If it didn’t apparently you can get flight reservations for about £10 to satisfy airline. Then just extend another 30 days in country