The modern way to do this is to use an 8-bit micro-controller, such as the PIC12F508, PIC10F200, ATTINY9-TS8R etc.
If you don't want a microcontroller then there are counter+oscillator ICs such as the CD4536, CD4541 and ICM7242.
There might be a day when the above are no longer available so why not use a microcontroller? They're cheap, the programmers are widely available and using the built-in RC oscillator will give a better accuracy than an astable with an external resistor and capacitor. I could write an assembly program for a programmable delay of 5 minutes to 15 minutes using the PIC12F509, fairly quickly, even though I've not done it in years.