Hey there man just piping in to provide some advice.
You say you know the risks; thats good because I can tell you they are very real. Personally I've never experienced any problems from 25-I but it never felt like it was meant to be ingested. However 25-B put my friend into a comatose state....
http://www.bluelight.org/vb/threads/679079-25B-NBOMe-warning-bad-trip-non-fatal-overdose-1000ug.
That occurrence was at only 1000ug so seriously, be careful with these drugs. They have killed unexpectedly and have killed users who have done it multiple times when they were taking a smaller dose than in the past.
That being said if you are moving forward with your trials just to clarify, are these tabs complexed at all? That can increase the subjective effects especially when the tabs are 1200ug. 1.2mg is a pretty damn high dose of 25-i especially with the complex so I would figure that out before you do them.
On that note, I would certainly not start with anything more than 400ug and honestly I'd start even lower to see how you react. Even if it produces an underwhelming trip at least you know you can tolerate the material to some degree. From there wait at least a week and move up in increments of 100ug until you've learned the drug and what it will do to you at what dose.
As someone who has been in your position though, curious about the drug world and wanting to explore. I leave you with this advice;
DO NOT explore your curiosity with the NBx's of any kind whether it's NBOMe, NBMD, NBF, etc. How long these drugs have been around and how problematic they have already shown themselves to be is a very, very serious red flag. Theyre dirt cheap for a reason, and in the end, if that off chance happens to be you or your friend, saving 10$ from not buying LSD or something more proven than NBx's wont be worth the trouble and possibly tragedy that may occur. Please recognize the chances you are taking in doing this and reconsider. At least wait until we know a little more about them...But I know you will do as you will, so just, be safe I guess and have proper back-ups AND ABSOLUTELY DO NOT DO EARLY TRIALS ALONE. Seriously man I wouldn't type this up if the risk weren't there--heed the warnings around you, please.