Re: When to start sparring again.
I think you should begin sparring now. As you said you 've been training for a while so you must be ready.
Try to relax and explain the situation to your coach that you want to start at slow pace to let your body adjust to the difficulties of sparring seccions and get mentally prepared.
Try to find some specific sparring partners that have boxing knowledge and they don't want to kick your ass or humiliate you.
Last advice but very important you should not be too stiff and punch too hard because a) that 'll not help you learn much and b) you could make your opponent furious. You don't need that especially at the beginning.