Is "Construction times up to 12 months" considered a triggering term under TILA when advertising construction loans?

Depending on the context, maybe. As a stand-alone statement, however, you are discussing hammers and nails, not financing. Reg. Z applies only to statements about the financing.

In the context of spelling out what we offer to builders. Not an actual loan product.

If builders are the target of your ad, then Reg. Z doesn't apply.

1026.2(a)2 OSC as Richard said - it's under the definition section.

ii. The term does not include:

A. Direct personal contacts, such as follow-up letters, cost estimates for individual consumers, or oral or written communication relating to the negotiation of a specific transaction.

B. Informational material, for example, interest-rate and loan-term memos, distributed only to business entities.

C. Notices required by Federal or state law, if the law mandates that specific information be displayed and only the information so mandated is included in the notice.

etc....