For Sales Transaction
As per AS 9 on Revenue recognition, you should record the sale transaction in your books as soon as the delivery (with risk & rewards) passes to the customer & there is reasonable assurance regarding consideration receivable.
As per AS 11, a foreign currency transaction should be recorded, on initial recognition in the reporting currency, by applying to the foreign currency amount the exchange rate between the reporting currency and the foreign currency at the date of the transaction.
So you should pass the sale entry on the date of transaction itself.
Now regarding receipt of Amount: -
As soon as you receive the amount to your EEFC Account, you should pass the receipt entry of entire amount by debiting half amount to Cash credit A/c & half amount to Balance in EEFC A/c (can be grouped under Current Assets) & crediting entire amount to Customer’s account at the exchange rate applicable on the date of receipt. Any difference due to change in exchange rate on the date of sales transaction & date of receipt should be debited or credited to P & L Account as Foreign Currency Exchange Gain/Loss account.
Again at the time of withdrawal of remaining amount from your EEFC Account, you should debit the Cash Credit A/c & credit the Balance in EEFC A/c. The exchange rate for this transaction will be the rate on the date of withdrawal of remaining amount from your EEFC A/c & Any difference due to change in exchange rate on the date of sales transaction & date of receipt should be debited or credited to P & L Account as Foreign Currency Exchange Gain/Loss account.