We would like to postpone/delay the payment as much as possible.
We'd like to put off the payment as much as possible.
We are planning to delay the payment until the delivery.
「延ばす」は
postpone
delay
put off~
です。
ですので、「できる限り支払いを延ばしたい（遅らせたい）」は
上記の1,2の文になります。
「入荷がかなり先なので支払いもできるだけ先延ばしにしたい」でしたら
We would like to postpone/delay the payment as much as possible since the delivery is scheduled to be extremely late.
もし「入荷まで支払いを延ばしたい」ということでしたら、3番目の文のように言ってもOKです。
We are planning to delay the payment until the delivery.
① Our view is that since the shipment is quite some time in the future
we'd like to postpone payment until the latest possible date.
多少長くなりますが、これが一番丁寧で論理的な言い方だと思います：
「① Our view is that since the shipment is quite some time in the future we'd like to postpone payment until the latest possible date.」
ご質問者様のシチュエーションに応じていると思います。
ジュリアン
日本 
イギリス 
