"收到样品费后20天发货"用英语怎么说?

Shipment: twenty days after receipt of the sample fee.

The samples shall be dispatched within 20 days after the payment receival.

ship after sample fee was received

Goods will be delivered in 20 days after the sample fee received.

Shippemt will be effected after 20 days of receipt the charge of samples.
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仅供参考for reference only

shipment in 20 days after reception of samples fee,
或delivery in 20 days after receiving samples fee