That depends on the way you like to work.
I’m character-driven. The character has to speak to me strongly, tell me his or her story. Then I start asking questions, and asking “what if?” and we go from there.
Sometimes, a situation will intrigue me, a premise will intrigue me. But until I have a character to drive the piece, I’m stalled.
Some people work better from plot and shape characters to serve the plot. It’s personal preference.
Also, remember this is a playground. Don’t be afraid to switch up your process. Every novel involves a bit of reinventing the wheel. Insisting “this is my process” will often hinder you rather than help you. You’re trying to create, not follow a formula, even in genre work.
When you’re making a living off your work, then you have a “process” that works for you. Inevitably, just when you think you’ve settled into “your process”, you’ll hit a roadblock and have to change it.
By Jenny Storm. A young girl fights to save her horse trainer father's reputation when vicious rumors could ruin their lives. Purchase from 
I need at least one good character to start the story, but I prefer two or three. The MC gives me the story and I go from there.
Yup. I’m interested in the people more than the plot. While I love a well-constructed plot, if it feels like the characters are being manipulated too much to fit the plot, instead of reacting as fully-rounded individuals, the writer loses me as a reader.
I so agree.