From Box Office Mojo:
Alien: Covenant delivered $4.2 million from Thursday night previews, which began at 7PM at ~3,000 locations. This compares favorably to Mad Max: Fury Road, which brought in $3.7 million on Thursday night before opening with $45.4 million. In fact, this is a better preview result than 2012's Prometheus, which brought in $3.6 million ahead of its $51 million opening weekend.