leaving 2 columns blank unless another is filled

So follow up to my early question:

I would like to move the new balance to the "Total left" column after a payment is made(I will manually do that).

I would like the "total after payment" and "months left" columns to be blank unless I mark the column "payment made" as completed.

So for instance: C is a column for "payments made"

B is the payment I make(with processing fees or whatnot)

D is "total" meaning how much is due right now

E is the minimum payment due

G is "total after payment"

H is "est months left"

So B is how much is coming out of my account (budgeting income and whatnot)

Once it's paid I mark C

D stays static as how much I still owe (mortgage, loans, etc.)

E is how much the minimum payment is required

F is interest rate

G is how much is left after the payment is made (from E) [=FV(F7/12, 1, E7, -D7)]

H is how many months are left [=NPER(F7/12, E7,-D7)]

so is there a way to make G and H blank until I mark C?