I got started diving with a PADI Discover Scuba experience. I was at a rustic resort where the activities included sea kayaking and snorkeling. I was skeptical of my ability to learn to remove and replace my mask under water, which I knew to be a requirement of certification, but I wanted to find out what scuba was like.
In shallow water from the beach next to the pier I learned some simple skills, such as partial flooding and then clearing the mask, etc, and then we went out on the boat and dived to 40 feet. I had issues with seasickness and equalizing, so it was not until several days later that I decided to continue.
The Discover Scuba experience was counted as the first day of a 4-day OW class, each day having a shallow-water and a deep water component. I could, in hindsight, have saved some time at the resort if I'd done the classroom and shallow-water classes in a pool at home before going to the resort, but I needed to do the Discover Scuba before I knew if I really wanted to get certified. So for me, it was all good.
When I went back for day 2 of the course, the seas were not quite as rough, and I had less difficulty equalizing, but one lesson I learned is that I cannot dive in rough water because I'll be too seasick to enjoy it by the time I get to the dive site.
I'd encourage anyone who knows they want to learn to dive to take the pool and classroom classes at home before their trip, and then they can probably do the open water classes in a couple of days, or a couple of hours a day for four days.
But someone who is interested, but unsure whether they really want to do it, might do well to start with Discover Scuba as a way to experience what it's like to scuba dive, and then continue with the full course, of which they'll now have done the first quarter, if they enjoy it. Where I got certified, Discover Scuba was really the first day of the 4-day OW course.