I wouldn't do Disco secured. Give it a few months and try to get the unsecured one. If not you will spend 7 months with a $200 CL trying to put enough usage through it to make a good enough impression to unsecure. Then you get to wait 90 days for a CLI once you unsecure. With your TU score you will get a good SL when you qualify.
Experian: 677 (28) | TransUnion: 697 (27) | Equifax: 684 (6)
Gardening as of: 1-23-2018
Updated 1-25-18