Wait time depends on branch and needs of the service, if it is submarine service then it is 3 to 6 months, seaman specialists are over a year to go to Raleigh. Between Phase 1 and 2 is usually over the weekend or a week or two in hold over, however if for any reason your BF is back classed, for injury, flu, bereavement, not passing 3 kit musters, discipline etc then he would be in hold over until the next course start date for his branch would be and there can be months between course start dates, this not uncommon but most well prepared people won't have to be back classed. Not sure he would be allowed to take leave during hold over since you need your leave to cover Christmas, Easter, summer holidays during phase 2 but he would be allowed to go home on the weekends.