Been at it about 15 months and like you had a history playing brass instruments. Guess I would qualify as advanced beginner at this stage. Play about 10 tunes from memory and another 20 using TAB( a form of written music that graphically shows the strings rather than standard music notation). Tried a couple of different books and settled on instruction from Jack Hatfield - published by MelBay. Jack has his own website - Hatfieldmusic.com. Started with First Lessons and then Book 1. About a third of the way through Book 2. They all come with a cd that has each exercise and song at several speeds, including at full speed with accompaniment on one track and banjo on the other .
Since you can count time already, its just a matter of learning the various picking sequences to get started. AS with anything, the learning curve is pretty steep at the beginning, but it didn't take too long to produce a recognizable tune. Speed comes with practice - which I still look forward to doing!
Didn't use the Hatfield arrangement for Cripple Creek, but went directly to Scruggs' version. It's written in 2/4 time, not 4/4, so don't be shocked when you see 32nd notes. If you leave out the up the neck part, you can probably have a recognizable tune in a month. At 15 months, I can probably do it at 150 BPM in 4/4 time. Not the 200 BPM like the pros, but plenty quick to sound good.
Go to Banjohangout.org. Lots of good stuff including the forums.
Have fun!