Drain on side stand with oil cap removed too, when more or less stopped replace sump bolt without doing up mega tight, it won't leak.
Now put bike on centre stand, on level flat ground.
Get ready to catch oil as well when removing old oil filter, i find a chain wrench works the best..
Smear some oil on rubber seal on new oil filter, screw in, and nip it up NOT TOO TIGHT, the oil and rubber combination will create a seal, do it up too tight and you'll regret it when you go to remove it next time.
You can start with exactly 2.5 litres of oil with no worries.
Put oil cap back on.
Start engine and run for 20-30 seconds.
Switch off then keep an eye on the oil window, a good torch can be useful to see the level, it eventually needs to be about two thirds up between the upper/lower level markings next to the window.
First go may not be enough oil, so ADDING VERY LITTLE OIL AT A TIME, repeat above steps, cap back on, start engine, let it run, switch off, and watch the window carefully until it settles again, which will take about 15-20 seconds each time at a guess.With a new filter you'll roughly be looking at about 2.7 litres in total, so don't start pouring huge amounts in and overfill it, as that can cause other issues, just take your time and you'll do it correctly first time.