Multiple If statements question

I am trying to enter a formula that says if A1 - A2 > 784 then display whole number result + 1. If result is < 784 display 1. If A2 > A1 then write "Done".

I'm filling boxes that hold 784 items. If I need 5000 items and have 0 so far, I want to divide it by 784. Since the result is 6.3, I will have to include a partially filled box. Thus the +1.  The result will be 7.

A1 is how many I need.

A2 is how many I have so far. Starts at 0.

Once I have enough or more than enough I will enter "Done".

My formula so far is =IF(A1-B1>0,((A1-B1)/784),"Done"). That only gives me Done if B1 is > A1.  I need to fill in the rest.

I hope all this makes sense!