Wali of a christian woman?

Salamwalaikum, I intend on marrying a christian woman who has already been introduced and accepted by my family and her family knows of me too. I’d like to get the nikah done as does she as soon as possible so that we can meet and spend time together more comfortably. Although, I have come to know that the wali of the woman has to be of her religion being her father, although because of our young age and her father still not comftorable with her marrying a muslim, she cant bring up marriage around him as it will anger him as she has hinted at it in the past and it didnt go down well. What is the permissibility of me going straight to an imam to act as her wali or do I have to directly seek permission from her father and if I get a no slowly go down the list of possible walis for her. My idea is we’d do a nikah for the sake of making relations halal as her parents are more akin to dating and want me to be around her for a few years before marrying, which as a muslim I cannot do.