Places - aka beginners - as it is called in AU, is typicaly (again, in AU) 5 minutes before curtain up. Normally, since I call beginers ("Ladies and Gentlemen of the X company, Act 1 beginers thankyou, act 1 beginers. Please ensure all beginners are in place and ready to start the show."), if the house is being held, I just dont call beginers. If there is a long delay, I will give them a call ("Ladies and gentlemen of the X company, the show is being held for x minutes due to..." followed by an auditorium message "Ladies and Gentlemen, welcome to this evenings performance of X. Unfortunatly, due to (Technical Difficulties|Bad Weather|Other Emergancy) tonights performance will be delayed for x minutes. We applogise for the inconviencience and would like to take this opportunity to remind you that flash photography......")
My policy of no tallent in the wings after house opens and no one in the wings until I call beginers means I dont have lurkers.
All ops in position at 15, especially flymen. Crew I usually keep in the crew room until beginers unless they are required.
It is all personal style, however there are union rules regarding a number of things.
House manager basically has control of the house and gives you the go-ahead to open the show. Basically, you hand over control of the house to the house manager when you give the go-ahead to open the house, and then they give back control of the house when they give you FOH clearance. I usually stay in close contact with FOH - they usually either have cans or a two way radio - so that I can anticipate when to call beginners.