The best way to drive a relay from the output of a 555 timer is with a diode. Anode to pin 3, cathode to relay coil, other coil lead to ground or
negative rail. Only works for coil currents up to 200Ma as this is the ratings for the 555. If the coil requires more than 200Ma then a bipolar or power mosfet will work as a driver. With multiple 555's, erratic operation can occur unless each 555 has a bypass capacitor from pin 8 to the negative rail very close to the 555.