Your wife can begin receiving reduced retirement benefits at age 62 on her own earnings record.  If she is entitled to a spouse's benefit higher than her retirement benefits, she would normally get a combination of benefits equaling the higher spouse benefit. This is usually 50 per cent of the amount that you would receive at age 65.

However, If she chooses to receive a reduced benefit before full retirement age, she is not entitled to the full 50 per cent spouse's benefit rate when you begin receiving retirement benefits.  A reduced benefit rate is payable for as long as she remains entitled to spouse's benefits.
 
You can file for retirement benefits online.