If you have ever tinkered with a telephone, you are familiar with booting in recovery mode. You are probably used to using a combination of hardware buttons to recover, usually with the power button and one of the volume buttons. The thing is, you don't really have to press the on / off button.
While your phone is on, open the flow menu and select "Restart" to restart your phone. While it is restarting, hold down the Volume Up button. When your phone is turned on, you can release the button and you are now in the recovery – as I said much faster .
You still have to hold down the power button and then press the Volume up button to to get past the "No order" screen for inventory recovery, but if you start with TWRP it starts up immediately. It is also worth noting that some phones have a different button combination to restore. If this is the case, replace any button with the Volume Up button and keep it pressed during a restart.
Oh, and finally, this same trick for booting works in bootloader mode. Restart the phone and press and hold the Volume Down button and you are ready to send Fastboot commands.
Don't miss it: The screen of your Android casts flat in 2 seconds