This is my first time getting Botox. Will just one session be effective?

I became interested because I heard that Botox has the lowest barrier to entry for beginners! Lately, every time I look in the mirror, I feel like I'm getting fine wrinkles on my forehead and between my eyebrows, and my jaw muscles feel a bit bigger, so it's been stressing me out.

But since I'm really clueless about the beauty industry, I have a few questions, so I'm leaving a post.

Do you see immediate results after just one Botox session? Some people say that to maintain a nice figure, you need to get it regularly at least three times for the effects to last, so I'm curious how people usually schedule their treatments.

I've noticed a significant price difference between domestic and imported Botox. I'd appreciate your advice on whether it's okay for a beginner to just start with the cost-effective domestic product, or if it's better to go with the imported one from the beginning to avoid concerns about resistance.

Please share any tips or precautions that can help a timid beginner like me, who doesn't know much about grooming, start with peace of mind! I really need your help.