Ohmic
You can either calculate/simulate/measure the voltage on the gate and check it's datasheet or have a look on the circuit around it.
For example in your schematic there is only a 2m resistor between S and GND, if you drive it in saturation you have a source (pretty much) shorted to ground

Do you think that it will work in saturation?
If it was driving a load (led, motor, etc) then the chances of being in saturation increases.
Ohmic is used when a voltage controlled
resistor is needed. ie amplifier circuits, load circuits etc...
Saturation is used when you need a voltage controlled
switch. ie driving a 12V line from 3.3 signal. Usually you will have a binary "control signal" (high - low, voltage levels depends on circuit)