@devilgospel
Is it smokable gear? If so, I'd suggest chasing a little piece off foil to check the potency and then deciding on the size of the piece that you will be smoking from, since each hit is (relatively) small, the onset is almost instant.. Plus you aren't taking your entire dose in 1 go, but rather over the course of a number of hits, I'd say t's rather hard to OD on heroin when you're smoking it.
If it's not freebase, then sniffing it sounds like the next best plan. But as you yourself said; start VERY low and give it enough time to fully start working before you decide to redose. Snorting it has more OD-potential because you're taking in your entire dose (usually, but I suggest you don't - definitely not when doing it the 1st time!) at once. Also it takes a while to fully kick in when sniffed. So if you're titrating your dose up, please make
sure that the effects are not still increasing, as it might be risky that way.
I don't know of your tolerance, but if you're very careful; respect the potency of the drug you're using and always use common sense. It
can be used safely by pretty much everyone (well, unless you're like allergic or something), even opiate naive people. But it's one to handle with care. I'd make sure it wasn't cut with fent or its analogues too before 'diving into' the stuff, though. Wouldn't know where to start to make sure of that, except send over a small sample to a test center (though they aren't available every where as I understand it), also they require a 100mg sample, if I only had 200mg there's no way in hell I'd send em 100mg to test.. Maybe I would send like 50 or 25mg, cut (by myself) with flour. Then take the results and multiply by 4 or something. :D But I digress...
Be careful! Be safe! Don't forget to enjoy it though!
OT: 80 mg oxy (IV), gonna take 0.25mg clonazolam in a moment, maybe some clonazolam too but gonna go slow in upping the benzo dosz then put on some netflix and since I'm already nodding of while typing this, catching a good nod will definitely not prove difficult! :D
Have a good one BL-buddiez!