I've never used a cup before, but I know for certain, you can't really do that with tampons, because it would be way too dry and eugh, even imagining that is making me shudder. Most women who use tampons know how unpleasant it feels to pull out a dry tampon; I have to be careful near the end of my period not to use a tampon with too high an absorbency if I want to avoid this. I may switch to pads near the end.

Periods can come without warning though. Some people have a super low flow early on, so they might get more warning (if they go pee and there's a lil blood when they wipe), but also sometimes it's heaviest at the start, which is why many women have embarrassing stories of their period taking them off guard and bleeding through their clothing onto a chair or something. Someone might wear pads if they're expecting their period - you can get lighter absorbency pads that might suit this better. Older women might wear pads like this at other times - my mum occasionally pees a little if she sneezes too hard, so she wears lightweight pads at other times of the month.

It's easier if you can predict when your period will be. I've never had a regular cycle, and I thought the whole "my period is 2 days late and I'm anxious that this might mean I'm pregnant" thing only happened in movies until a friend anxiously messaged me about it. Turns out some people do have that level of regularity - I might actually ask my super regular friend what she does when expecting her period, come to think of it. But yeah, for many people, it can't even be predicted to the day, or even the week.

Edit: reading other responses to your question made me think of amother point: even if you have irregular cycles, it can be possible to predict by various bodily signs. Something that I don't hear talked about much is how vaginal discharge changes over the menstrual cycle. When I'm ovulating, there tends to be more discharge, and it's slippery and clear, almost like egg whites in texture. At other times in my cycle, it might be more white coloured, or more creamy, or more sticky. I find it gross and fascinating in equal measure — sometimes I'll just stick a finger up there to check if I'm unsure where I am in my cycle

My wife uses a panty liner when a period is coming up. For my wife at least, it usually comes on light at first and she has a chance to notice when exactly it hits by checking the liner. And once it actually starts then the tampons are used in addition to the liner.

You can’t wear tampons very long so just a pad if it’s about that time or feels that way. Typically I know to do so when I’m turning into a honey badger emotionally.

Carry tampons at all times.

When the monthly misery ends i block out the whole experience and the very existence of menstruation until next time, when i am shocked and angered that this is happening again, already!?! I'm looking forward to menopause.

Everyone is different and bodies change over time. That being said, at this point there’s a discoloration in daily discharge the day or two before Aunt Flo arrives. We Know. And period underwear is a game changer.

I like how you had to clarify that your question is aimed at women, and then proceeds to ask a question about menstration.

I stopped tracking my period at all cause I just have a sense for it now and it was annoying when I'd forget to log a period and my tracker would tell me ridiculous things like I had a 97 day cycle or something. Plus privacy concerns. The only time it becomes inconvenient is when a doctor asks when my last period started, which usually just illicits an "I dunno, not abnormally long ago" at which point they ask me for a firm estimate and I throw out a bullshit number that will get them to move on to more pertinent discussions. I got an IUD last year so varying cycle lengths and missed periods aren't without a reasonable explanation.

Anyways, I usually get a dull ache in my upper thigh/lower abdominal area the night before as warning. Mine start out pretty light, so a simple panty liner will keep me covered for the first handful of hours the next day. Honestly though I think I usually catch it by wiping after doing my business and seeing a trace amount of blood there, before I see any in my underwear. Although there have been other times that I just got a sense of moisture at a point, so the panty liner is a nice layer of security.

If I'm going out of the house I keep some regular pads on hand just in case the time comes to bring out the big guns. Menstrual cups are also super safe to get ahead of the flow with though (no risk of drying you out and causing micro abrasions like with tampons) so there's been a few times that I just popped that in from the jump. My workplace also keeps emergency pads stocked in the ladies room (as a last resort, those ones are SUPER bulky for some reason, way overkill)