New device galaxy s6

Hey folks I've just now upgraded to this device and have been a dev for write some time now but mostly for HTC. My firmware and kernel are predated may of 2015 so I'd like to get suggestions from users that have had experience with the s6. What I'm looking to do is sim unlock, root, run twrp recovery, and eventually build roms for this device. So where should I start, take the update first, then sim unlock, root, & recovery, or do all of this now before I update my firmware using the ota? I've read that we can access root with 5.0.2 & 5.1.1 but what's your opinion? I would rather not trip my Knox but it's not a deal breaker if I do, since I own my device. Thanks in advance for your input. Oh and I'm not a noob and have read all the threads here. It's just a little confusing where to start since the device has been out a while now. You're all ahead of my game a little bit. Lol

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