The Log time debate has been going on for a long time and most people agree that if you are in an aircraft with the engine started, for the purpose of flying, and you are actually getting off the ground, you can log it, until you are back on the ground and turn the engine off, basically Hobbs time.
I do not know of anyone that has challenged that.
That said there are some apps that will let you Track the flight and generate a .kml file that starts after the aircraft is moving, over 6Kts, and you can use that. There are others that want gear off the ground to gear touching the ground.....
As to the IMC / IFR most pilots will overstate that time. In many locations you are on an IFR flight plan and you may only get 3- 5 min. of IMC. Most pilots will log that as at least 0.1 Hr. which is very common, the tendency is there to log something regardless of it being exact.