I put it on the center stand - run it for 3 minutes. Then wait 2 minutes and check the level in the sight glass.
Not checked the airbox... It has a DNA air filter with the open plate thing....
Checking the airbox, is a case of removing the air filter and having a look?
No, just inside the airbox itself for oil residue. I'm still learning the particulars of this bike and can't remember if the crankcase breather tube plumbs into the Himmi airbox. Many bikes do due to emission requirements. The last three bikes I've owned I disconnected that hose and terminated it with a small screen to prevent crankcase vapor from depositing oil in my air box.
If you have high crankcase pressure, like from ring blowby, you'll get an abnormal amount of oil in your airbox, same if you overservice your oil. But you're checking the oil properly so overservicing isn't an issue. That's why I asked you to check the airbox. If you have a lot of oil in there and you're not overservicing then possibly it's from excessive ring blow-by, due to worn rings, glazed cylinders from improper break-in etc... That would contribute to higher than normal oil consumption.
I'm not familiar enough yet with the Himalayan to judge excessive oil use but based on comments here and other threads I've read, with your mileage, it does seem a little more than normal, but I've also read of owners that have had similar oil consumption as yours and has remained stable for thousands of miles that way. I'm sure members here with much more familiarization with the Himalayan than I will offer opinions as to what's considered normal.
Several factors can contribute to excessive oil consumption so just trying to help isolate them. Under normal conditions and your mileage you don't normally see a noticeable change in a 1700 mile interval unless something has happened or changed. Different oil? Leaks, Valve guides, rings etc...? Just speculation until you start isolating possibilities.