I'm honestly probably the dumbest person to ever make it in banking...

Hi Everyone, 

I have to admit I'm lost for words because I finally received an investment banking senior analyst role offer at a BB bank (Goldman, MS, JPM, Citi, BAML) after working at several chop shops (got into banking very late but decided to stick with it even if I felt something else would've suited me better) and literally getting grinded to the ground sending calendar invites (Ok that part was a joke). I was making severely way below street at these places (base below ~$65-70K as a first/second year and currently about the same now sub 80K...) but now I have managed to land a full-time offer and I will have to really step it up. Not sure how I was able to get it and though I was an auto reject after first round but kept getting moved on. I am also not very good at interviewing and really bad at technical questions so in complete shock.

SORRY for all the negativity here but need you guys to understand how i really feel right now and where I'm truthfully coming from.

Anyways I would really appreciate and welcome any advice/suggestions on how to best prepare myself for the job. I'm so nervous because they are expecting me to know how to model (NEVER HAVE really MODELED during my analyst years...I know pretty sad) and obviously join as a wizard at excel, which I only know basic functions and constantly find myself working inefficiently since all I know are shortcuts and only very few formulas (Don't even know Vlookup, hlookup, macros, index match, find myself running SUM functions numerous times instead of sumif/ifs.)

I really do not want to screw this opp up and think my offer is a mistake but they asked for HR asked for my information. If someone has any advice on how to best prepare, I would greatly appreciate it. I have less than 2 months until I start and really do not want to come off as a complete idiot since everyone at this bank probably was doing what I am currently capable of when they were a first/second year analyst. I am going to do whatever it takes and prioritize this over my deals that continue to die. If you have any opinions on choosing BIWS and WSP please let me know as well. I just really want to sit down and actually take the time to learn all this stuff and stop faking it until I make it. I desire to become a excel and financial wizard where everyone goes to you for help in the office. Thank you!!!