How to make sure you can lock in the new champ before other people in blind or draft

You don't. Blind Pick is a shitty system that promotes auto locking champions and roles without calling it, which is just plain toxic. I don't suggest you play that mode for any reason if you don't intend to "fill".

Draft Pick is fine, but you're still not guaranteed to get your choice. New champions are often banned out, so even if you have pick priority it could still get banned away.

If you want to ensure you get Kindred, play Team Builder. You are guaranteed your champion and role.

Copy and paste their name into the search bar as soon as champ select loads, then click the icon asap.

tbh i havent had trouble getting her. no ones choosing her in my blind picks