My experience (from a long time ago, over 10 years) is 8 to 9 weeks.

Here are my eggs (laid July 11th) at 5 weeks -

It looks like all 10 of mine are still good - the brown on two of them is staining from the coconut fiber.
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3.0 WC; 0.2 CB L. getula californiae
0.1 WC; 10 eggs (7/11) Elgaria multicarinata multicarinata