Don't delay the 1.5 yr old injection for more than 4 weeks unless the BB is not fit for injection.
It is a very important and last injection for BB before BB go to school.
If you want you BB go to N1, your BB must complete all requred injections (i.e. up to 1.5 yr. old).
For PG, do give your BB have reular lessons. Find one suitable and let your BB go there for at least 8 lessons to see if your BB suit the teaching method. 1.5 yr old is a high time to go for PG.
My son who born in April 2003 will go to PG very soon if the teacher of my girl will open class for BB.
The teacher is very famous in teaching kids. She is a pianist and the ex-director of Tom Lee Music courses. If you are interested, please contact me and I will inform you of the details later after discussing wit the teacher.
My girl went to PG when she was only 1 and it was very good to her. She acts quick, speaks well and gets along well with others in school.