I usually did it in my room, mostly at night in bed before going to sleep. It wasn't an issue.
Though once, I got a free purple dildo off the internet (no clue why it was free!), which was mailed in a plain cardboard box with no hint of what it was or where it was sent from, so my mom wouldn't know what it was. I hid it in a pile of spare blankets and whatnot by my bed, and my mom liked to snoop through my shit and found it. I wouldn't have known she found it had I not looked for it one night and noticed it was just gone. No one said a word about it, but I knew it was her that took it.