Yes, as Mr Z wrote ... for the first week or so take it really easy and slow. It's not a competition against the clock.
After a few days your scalp will begin adjusting to the regular shaving and will become tougher. As you gain experience you will know how best to shave your head - certain spots will need more attention or shaving from a different direction. And the time required will reduce.
When you are not balding you will notice the return of stubble from hair growth - how much and how quickly varies with every person.
But the experience and appearance of a well-groomed bald head makes it all worthwhile.
Good luck. Post back as you have more thoughts, questions or anything to add to the conversation.