Thank you for your query
Firstly since you have started the vaccination
in time there is no need to worry. He is not likely to get rabies
. Secondly for the wound, the trend has changed a bit in the recent years. Anti rabies serum is injected directly in the wound and intramuscularly (half and half dose) and even larger wounds can be sutured. It is especially followed for wounds on face etc. However if the wound was dirty at the time when doctor saw it then washing the wound before suturing it is the right approach. The presence of pus shows minor infection but it is not suggestive at all that your son will get rabies. It is just bacterial infection of the wound. With good dressings and antibiotics the wound should heal fast. Depending on the size it may heal spontaneously or may require suturing.
Hope that helps
God bless you