As a teenager or for however long you've lived with them. I do it when they leave for work, I know they wouldn't be pissed off or considering it disrespectful since my mum told me that I can bring my "boyfriend" (who's actually my fwb) over anytime I want. My dad doesn't know though, it's been going on for approximately a year and a half and I don't plan on ever telling him 😂