Nope you don’t need to cut them at the same time
. You just want to cut them when they are actually ready.
Yours are really looking farther along then I expected for being at 6 weeks based on what people usually post lol. Are those 2 different buds in those pictures or just different angles?
I’d say you are right on track for an 8-9 week harvest. The stigma(pistils/hairs) are turning red it looks like. Once that is mostly complete the buds will swell up internally. They won’t look much bigger on the outside but will get denser and fatten up the bracts(calyxs). The plant adds a significant amount of weight and bud density during this swell period.
Then about 2ish weeks after the stigma have changed, and the buds have swollen some it is time to check the trichomes and determine the final harvest point.
It takes weeks for plants to mature and ripen fully. Don’t be in a hurry and just ride it out. It’s very easy to harvest plants early and not reach their full potential, but I’ve never seen someone accidentally over ripen a plant. It just doesn’t happen.