the tinctures are preserved in a pretty pure alcohol, so they should last a very long time.
When I'm 'on schedule' I take CB in the morning and Coptis at night. Don't have the curcuma, but if I did, I'd alternate between Coptis and Curcuma. This is my regular schedule until a flsuh comes up - then I switch to GCG in the mornings and Coptis at night. I believe those are Julia's recommendations too. :)