Cheryl the seedpods take appr. 9 months to mature. Before they 'pop', they will start looking dull and a crack may appear along the center. A net bag is a good way to catch the seeds.
If your plumeria is a variety of Plumeria rubra the seeds will not come true to the parent, so you can actually have a new variety.
The seeds of the other species do come true. Can you show us a picture of the flower and leaf? that will help.
And congratulations!!
