Check out this implementation of Arduino code https://github.com/fbiego/ESP32_BLE_OTA_Android
I was able to transfer the update.bin file via BLE from the phone to ESP32, 1005392 bytes in 5mins 20sec

I have implemented an Arduino code (1005392 bytes compiled) which takes around 5mins 20sec to upload the same file via BLE.
The Arduino code is available here https://github.com/fbiego/ESP32_BLE_OTA_Arduino along with the Android app code https://github.com/fbiego/ESP32_BLE_OTA_Android

I wrote an Arduino Library to set and time
https://www.arduinolibraries.info/libraries/esp32-time