While I realise it's not really what you're asking, I would say as a general rule you should avoid being in a restricted area during its hours of activation when they notified by NOTAM or ERSA. Being in the airspace at its advertised time of activation is akin to flying through an active restricted area. That said, the military controllers have always been very accommodating in my experience. Obviously there's nothing you could do if an unplanned activation of the airspace occurs.