Each child has different needs in adapting to new realities/routines. Entry into the daycare/nursery/kindergarten is always a source of concern for parents.
A good option may be to spend some time with him on the first day and assess whether he is integrating and helping him to do so: helping to find toys, showing all spaces, establishing relationships of trust with caregivers, introduce the other children…
Another important aspect is our example: our children instinctively react as we do (as a mirror), that is, if we are anxious, they will show signs of anxiety, if we do not trust the people who will be their main caregivers, they will not trust them also, and so on.
That’s why I recommend that you take a deep breath, trust that it will go well, leave the clock at home on the first day (go without time to leave or come back) and focus on your child and help him discover the news!
He will give you all the signals you need to evaluate how you need to proceed in their adaptation!
Once you see that he is integrated, set a goodbye routine (kiss and hug, for example) and leave. This may not happen on the first day, but it must happen someday. Do not try to leave if you´re not confident that you should leave. When you start the goodbye routine it’s a non-return point that you should not come back from.
After you leave alone, if your heart gets tight, it’s normal! If you want to cry, cry! That’s why it’s so important to make sure that you’re doing your best for your child and you´re comfortable with it! Make also your own adaptation to the new reality, but without interfering with his (and preferably without him realizing it).