**Adding this: if you send him to preschool at 1:00-3:30.... is this usually his "nap time?" Usually a kid is tried by the afternoon and especially if he is used to napping. And has spent the morning with the Nanny. Thus, if sent to preschool at this time in the afternoon... he may be tired... maybe too tired to go to Preschool at this time, and then to interact/engage/act accordingly??? Something to think about. Thus, maybe sending him in the mornings are better..... (ie: think about 'timing' and what time of day is best for your child when HE is at his best... not tired. Otherwise, you can't expect him to just get in the swing of things right away at school, if he is tired at that time of afternoon).
Also, if not having a nap because of his Preschool schedule, do not "assume" that he "will" be going to bed earlier, as you plan or think he will. Sometimes, lack of naps, does not mean the child will then automatically go to bed earlier... and well.
Sometimes, an "over-tired" kid, will actually NOT sleep well, nor fall asleep well.... because over-tiredness actually makes it harder for a child to sleep or sleep well.
Also, how come the preschool hours of his attendance is "only" 2.5 hours??? Usually, Preschools are half-days or full-days....
By the time he gets to preschool and adjusts and starts to have fun, it will already be time for him to come home. 2.5 hours to me, is not much.
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Send him.
He will be fine.
You will be fine.
Everyone will adjust.
When I had my 2nd child, my daughter started Preschool at about 3.5 years old. She was close to me, as your son is. She spent all her time with me, since I am a SAHM. And she is bi-lingual. Both my kids are.
She did FINE!
And, I then had time just with my newborn son at that time. It worked out well.
However, my daughter went to Preschool, initially, in the morning... 3 times per week. Half days. Then, after that, she wanted to go everyday. So then she did.
Going to Preschool was HER time... HER thing.... and to have fun with other kids, ASIDE from just being home with me and a new baby. So it was beneficial for her, in that way. She LOVED preschool.
For you, and your son... I think, him napping is still important... but it seems with his 'new' preschool schedule of going to school in the afternoon... he will not be getting naps. As you said. So my suggestion would be: that he go to Preschool in the MORNING.... and be with the Nanny after that, or with you. To me, that makes more sense. For a child.
And that way, he will then be getting naps. And his same bedtime schedule... not it having to change, and then him being without naps....
Because, him going to Preschool from 1:00-3:30... to me, that is a kid's "nap time."
Afterschool... kids are typically tired. This is normal. And then they nap once home. Or, in Preschool, they have nap periods, usually after lunch. I would time his day/your day, according to that. More convenient that way... and keeping it in line with his nap times too etc.
To me, going to preschool in the afternoon... is working against any nap time, for a kid. It deletes it.
all the best, just some ideas,
Susan