This is a self triggering, 29sec, monostable delay timer circuit. Pressing the push button once "latches" it in the ON position. The timer output will remain on for the time duration set by the 2 caps and the 51k resistor. To restart the timer, press the switch once to turn it off and then again to turn it back on.
If at any time during the ON delay period you wish to terminate the output, just press the switch to turn the timer OFF
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You'll have to find a SPST "Latching Push ON - Push OFF" switch,
like this. The added diode (in this case, a 1N4148) is for rapidly bleeding off the 2 caps between power application(s) of the timer. This will maintain the accuracy of the delay timing when re-powered (everything starting as close to zero as possible).
Other than this circuit, there are no 555 latching timer circuits whose output can be toggled between On and OFF with only one SPST switch.