Various examples and schemes pertaining to timing advance validation for transmission in preconfigured uplink resources in narrowband Internet of Things (NB-IoT) are described. When in a first mode, an apparatus (e.g., a user equipment) receives a plurality of different values for a time alignment timer (TAT) from a network before entering a second mode from the first mode. When in the second mode, the apparatus selects one of the plurality of values to apply to the TAT and also starts the TAT to count. When there is data for uplink transmission while the apparatus is still in the second mode, the apparatus performs an early data transmission in an event that a timing advance (TA) value is valid and that the apparatus is in the same serving cell as it was before entering the second mode.