Bill received but Entry after receive amount

Create ledger Advance to Mohan A/c , under Loans and Advance , Asset side Balance sheet .

When you pay Advance to Mohan pass entry .

Advance to Mohan A/c Dr 50000/-
To Bank. A/c Cr 50000/-
( Being advance given to Mohan )

when expense approved and bill submitted
then pass entry

Expense A/c Dr 28000/-
To Advance to Mohan A/c Cr 28000/-
( Being Expense adjusted against advance given)

Balance 22000/- will be reflect to his ledger.

In between Mohan say I have send the bill of 30000. How and where I check that 30000 bill received by mohan and under process for approval?

Pass second entry only after physically available bills as documentary evidence approval .