When I started using the cup (first a Keeper, later the Diva), I could NOT make it happen, not before kid, not after kid. I was all pushing and prodding and rooting around, lol. One day, a friend of mine who also used one said she needed to dump her cup (because we're open about such things), went into the bathroom, and came out like 30 seconds later, done. I was stunned. What the?!? She was confused as to why I was stunned, and asked what the heck happens to me in the same process.
Once in a while it pops in beautifully; most of the time I'm still poking, prodding, twisting, rooting for up to two minutes to get it placed properly and completely unfolded. It's a whole event for me. I did read a couple of helpful tips on the DivaCup webpage -fold the cup, squat, go in at a particular angle, turn it a couple of times. Those helped a lot, but it's still silly. Wetting the cup in warm water also helps me.
The other aspect to the cup I don't love -besides it not holding more than a couple of hours of my profuse bleeding at a time and being difficult for me to place- is public washrooms, or any washroom in which the sink is far from the toilet. When I use the cup, my hand gets very bloody. I don't mind that at all, but I totally mind being stuck in a cubicle with a bloody hand, and also not being able to wet the cup for easier insertion... Or in NZ, when some washrooms had the sink in a room separate from the toilet room. Tricky, potentially embarrassing.
And I still use it, go figure! I do like it infinitely better than pads. I prefer tampons, but I choose the cup for environmental reasons and to preserve plumbing systems.