伺机而动

伺机而动 [sì jī ér dòng]

1. ■ watch for the proper moment for action; keep secretly ready for the right time; see which way the cat jumps; wait for an opportune moment to act; wait for an opportunity to take action; wait for the opportune moment to go into action; wait patiently until one's chance comes; wait for the right time to take action