Alibaba trade assurance contract with supplier

I am about to place my first order from a supplier with trade assurance. They said the leadtime will be max 15 days. Now in contract it says

Seller should ship out Products at the designated Port/Place of Loading within 180 calendar day(s) after receiving Total Amount.

they say dont worry about it and the production time will be 10 – 15 days . Is this normal ? I am planning to not accept and ask for a change in contract . Anyone had similar experience ?