Efficient use of Construction Robots

Actually there is no way. The following workaround should help:

• place a roboport with construction robots in the target area (dont connect the port)
• place a yellow chest including all blueprint parts next to the port
• use blueprint
• after completition fill the gap of roboports to connect the robonetwork to your main factory

This way they will construct while you can place belts, or do whatever you want.

It's not as perfect as you'd like to have it, but this is the closest possibility to what you want to achieve.