Newb - belgian cherry question

Ok - I have brewed for 15+ years, but I am not experienced in sour beers or similar. I would like to try to do some beers in this area. I recently brewed a Belgian Golden Ale. Fermented it with 1388. Primary ferment of 3 weeks. I then added 24 ounces of montmorency cherry concentrate and it is now in secondary.

I was considering bottling half of this beer as is, and taking half and possibly souring it in some way. Would this be a good candidate at this point to add lacto or brett or some yeast blend? Looking for kind of a tartness. Is this something I can do at this point in the process or should I have started earlier?

What "bug" would be best to add at this point (if any) to add the tartness I am looking for?

Thanks

If you are just looking to add some tartness you could just toss in some lactobacillus. If you are looking for more of a funky sour like lambic or flanders red/brown you'll need to pitch and blend of brett and lactobacillus or brett/lacto/pedio. You can buy each separately but both white labs and wyeast make good blends that will get the job done for you.