One at a time... and backed by something like a TCP/LCP/P3AT auto as the 'spare' ammo.
See they are kind of heavy and slow to reload so one simply pockets a small gun as the reload. Now a TI S&W snub would be wonderful but when your snub cost more than the main carry gun it gets kind of ridiculous! Maybe a J airweight .38 DAO if you want a revolver for the reload.
I also suggest finding a mousey old revolver that is almost like the one you carry and shoot it often to get your skills up (and reload to so to cut cost.) With just six shots you need to be a better than average shot to make up for it, and yes I'm IDPA expert in all classifications and class 'A' IPSC and have state trophies in stock service (Glock) as well as revolver (stock service revolver.)
And if you are nuts like me you will get a all aluminum non-gun, used to make holsters, just like the carry gun and then at home draw from concealment alot to get gun handling skills.
And add a .22 version to cut cost down. Just yesterday I saw a S&W 18, 4 inch .22, a bit rusty, for about $300. I was tempted to get it to but I have a S&W 34 stainless snub just for that reason.
But hey, shooting is one of my hobbies and thus all that $$ for training is just furthering my hobby as well as defensive skills. Martial arts is my other hobby, done it since college.
"The government has confiscated all of our rights and is selling them back to us in the form of permits."