Noseeums are supposed to be worse at dusk. But we have not seen them respect the time of day. They are all "teeth". A decent breeze keeps them away.
On a full enclosure--if you get the very fine screen that keeps noseeums out, it restricts the breeze in lighter air. Big time tradeoff. We just finished building a complete bimini enclosure and used standard screening. Deet does the rest.