How do I post to General Ledger:

October 2 Ordered cleaning suuplies, $500

October 7 Received the cleaning supplies ordered on October 2 agreed to pay half the amount in 10 days and the rest in 30 days?

No entry yet on Oct 2.

Oct 7 dr. Cleaning Supplies 500
Cr. Accounts Payable 500

No entry to record agreement of payment terms.

If payments were actually made on the agreed dates, then:

Oct 17 dr. Accounts Payable 250
Cr. Cash 250

Nov. 6 dr. Accounts Payable 250
Cr. Cash 250