The ‘Power-up procedure’, presented in the datasheet, addresses your concern. Typically, the micro-controller can be made to wait for a specific time period before beginning the communication with the chip. The typical total delay for the chip to be completely ready for communication is about 66ms. So a time-out can be set for about 100ms before communication begins. But a better approach is to track the reset flag in the IRQSTATA register (Address 0x22D and Address 0x32D). This flag is set once the chip is ready to communicate and hence the micro-controller can effectively determine when the chip is ready.
This FAQ was generated from the following discussion: ADE7953 - ready for communication?