It’ll be 3 days _____ he _____ back from his hometown.[ ]

A. when; will come

B. after; will come

C. since; comes

D. before; comes

营业期间防抢预案规定，犯罪分子在柜台外实施抢劫时，要视犯罪分子所持凶器，按照“先周旋、（）、再报警”的原则，灵活处臵，充分利用防护设施保护自己。