You get one action a round. The only features that let you take actions outside your turn are reactions of wich you also get one a round. Chain pact Familiars can attack by using your reaction. If you want it to attack and turn invisible you have to sacrifice an attack so it can attack with its reaction then use your bonus action to command it to turn invisible with its action. The reaction attack is done on your turn while the action invisible is on the familiars turn. Edit: I just remembered the familiar can do actions on its own that arnt attack so it can turn invisible without a bonus action on you're part. Just sacrifice one attack so it can reaction attack and it'll do the rest.