It's going to be very hard to make a full party in 15 minutes unless it's peak time. And knowing how NA people act, even on peak time it will be hard to get full in 15 minutes. On off-peak times (When people are at work and school) I often wait 2 hours (2 PF recruitments) before my party fills up. If you really want to do the content, I don't think 2 hours is that much really especially if you have stuff like cooking/cleaning you can do while you afk wait.
Use the full 60 minutes to recruit people. The longer you recruit, the more your message goes to the top so it's easier to find. After 30 minutes or so, your message will become one of the top ones that people see as soon as they open up Party Finder.
Also the fastest way to get people to join your Party Finder is to already have people in the party. People are more often going to join a party that needs 4-5 people than one that needs 7 people. Getting 2-3 friends to join you helps a lot I find. If these friends have cleared the content, add that in your message. "Thordan EX beginning learning party. First timers welcome. 2 people who have already cleared are helping". This sounds a bit weird since I'm used to typing this all in Japanese but try writing something that sounds natural.
Also shout is a great tool as well. After 15 minutes or so, every 7-10 minutes I go to every popular zone and just shout what I'm PFing. "Sorry for the shout. Recruiting for Thordan EX in Party Finder. Practice party from the very begining, first timers are welcome. Need 1 Tank, 2 Healer, 2 DPS. 2 people who have cleared already are helping." Something like this. Again I normally type this in Japanese so it might sound a bit weird.
