My first thought is that you have about five months before your due date, and the puppy has likely got about 8 months of puppyhood left. But the timing seems to be OK to me because the baby won't be down on the floor creeping, crawling or toddling around until after puppyhood is over. Cinder's behavior around 4 - 7-year-olds is only partly indicative of how he will react to the baby. Often dogs instinctively understand that babies are, well, helpless babies, and will be naturally gentle with them. (My own observation is that this principle holds true more often with bitches than with dogs, though.) The dog's youth is likely on your side because he has not been part of the "dog pack" (as he understands life)long enough to feel that he needs to solidify his position as "number three dog" in the scheme of things. He will be likely to accept the baby without jealousy problems.
(I would think along those lines because I have always had dogs and had to get rid of one that lived in the house when my daughter was born. The dog, a German Shepherd, was quite jealous of the baby and growled at her every time she cried. I was afraid the dog would attack her, so the dog went to live with my sister-in-law.)
When you bring the baby home from the hospital, be sure you let the dog see and smell the baby. Pet the dog and speak reassurringly to Cinder while he checks out the baby. Petting him while he meets the baby also puts one of your hands on the dog, if you need to nudge him back for getting into the baby's space. Remember that a dog is intellectually equal to a 5-year-old child, and to Cinder this is the equal of being introduced to "a younger sibling." Use the tone of your voice to guide Cinder in how to treat the baby. Praise him for being gentle and sweet, scold him if he's too intrusive. Scold him angrily if he tries to jump on the baby. (Not likely he will, I'd guess, because you will be holding the baby.)
In the meantime, teach Cinder now not to jump on people, whether small children or adults. Being a puppy, he's enthusiastic and wants to make a show of his affection, but when your baby is a toddler, you don't want the dog knocking the child down.
I don't know how you feel about dogs licking, but you might want to teach him not to lick faces. Babies eat messily, and you really don't want the dog licking the baby's mouth. (I think that's just icky.)
Remember that the main factor in Cinder's reaction to and treatment of the baby is Cinder's own personality. (That German Shepherd of mine was naturally a bit fierce to begin with. She disliked strangers and considered herself "the tough dog.") But Cinder is an affectionate dog by nature, so it is likely that with a few directions from you, he will be just fine with the little one.
And any dog needs "a place of his own" where he can go when he wants to be left alone and where he can be sent when he needs a little "time out." Make sure his place is always available to him and that he feels secure there. We used a blanket on the floor for our other German Shepherd when our children were young. With the present dog (kids are now grown up), it is the corner of the living room where we used to keep her kennel when we crate-trained her. After she was finished training, we removed the door and left the kennel there for a few months, then removed the kennel and left the blanket there. It's her corner and she goes there when she wants a little time to herself.