I think that if the parents are safely isolated, they can safely wait a month. It may be even recommended to let people who are more in danger to go first. At the same time, any old person who is connected to any institutions (nursing home, hospitals, yeshivas) should get it immediately.
After about a month, we will have observational data on millions of people from Israel, US, and UK and we will see immediate effects across all age groups and health conditions.