Harvest white pistils or amber ?

Just a sidenote, going only by your pictures, you still look 4 weeks away at a minimum. As an indica dominant strain, you will need 9-12 weeks after the first pistils showed before you are ready for harvest.

Usually almost all the pistils will turn orange before she's ready to harvest but occasionally they'll stay white until you dry them. In this case, you need to check the trichomes. Clear trichomes are useless, you want almost all to be cloudy with 10-30% amber.

Use a loupe and check the tricomes, but in my opinion just based on the pics you have up, she is not ready yet, but worry about tricomes, not the pistils.,

You want some amber tricomes. The pistols will turn red/brown as bud dries. It does sometimes happen to stay more white but not often. I'd say your plant still needs time.