Here is an example of EEPROM device: 24C32/64
http://www.atmel.com/Images/doc0336.pdf
To complete Write data transaction, program must wait for Write Cycle Time (twr) before generate a new start transaction.
From below table: at Vcc 5V, write cycle time is 10ms. To store data into EEPROM correctly, program must not generate any new Read or Write transaction during 10ms.