No Finance background but got into Big 4 CF

I am a BBA final year undergrad with essentially zilch formal financial education, yet I am starting at Deloitte (US) Corp Fin. in a couple of weeks.. talk about hitting the jackpot.

60/40 Public Private engagements. Expected to deal with analysis, statements, cash flow modeling, valuation.

Now, I am doing an advanced financial modeling course (so I know about things - it doesn`t mean that I can do them and fully understand stuff...), yet it seems very unguided and shallow since I cannot connect the dots together. Almost possibly, it is because of the lacking accounting background and all.. What do you guys suggest where should the focus point be ? Nailing the relationship between the three statements ? Understanding the cash flow ? Or being able to use excel properly ?

As an undergrad CF intern, probably not much is expected, but what is absolutely crucial for me to know ? When does a big 4 company say that OK since you can do this and that so we won`t need our money back! :)

Please be so kind as to name things that should be nailed as opposed to referring to a course that has it, since I am already doing one..

Much appreciated folks,