How do I access Real-Time clock on the Xbee3 NB-IoT module ?

According to this>

Xbee3 cellular modules have a RTC. But I could not find any way to access it.

time.time() needs to connect to the network. But I need to start a timer before the module gets connected to the network. How do I do that?

You can use the time.ticks_ms() or time.ticks_us() to get the XBee’s time since boot in milliseconds or microseconds respectively.
Other supported functions in the time module are described in the XBee MicroPython programming guide here:|_____3