as already mentioned in my comment to the first answer the 2 expressions have a different meaning in German. Lieferfrist = certain period within an order has to be delivered; Liefertermin = fixed date;

I found "time limits for delivery" in a document stating the general terms and conditions of sales and delivery...maybe there is a more suitable expression.

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Note added at 2003-01-25 19:05:22 (GMT)
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...Time limits for delivery shall only be binding if agreed in writing...

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Note added at 2003-01-25 19:07:15 (GMT)
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...Any **dates or periods for the delivery **of the Goods or any of them are best estimates...
http://www.willcowells.com/terms.pdf

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Note added at 2003-01-25 19:14:31 (GMT)
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http://www.seepex.com/pdf/agb_e.pdf
..confirmed *delivery date*....*delivery periods*....page 1 /point 1.5

Doris' explanation is helpful. This just picks up on it by suggesting a way in which it might be said in English as our ways of saying Frist and Termin aren't quite so neat.

why not simply "delivery times"?
Before a certain date, after a certain date, within a period of time, they are all "delivery times".

(Given/indicated/offered and so on) delivery times are only valid upon ....

another attempt

the terms are the general expression for the dates and delays of delivery