https://www.moe.gov.sg/primary/p1-registration

Details for this year’s P1 Registration Exercise will be updated in May. Join our mailing list to receive an email alert when registration information updates are available.

然后MAIL LIST有个表填一下：
https://form.gov.sg/#!/5fe00a9d3479190011b95a3b

For parents with children born between 2 January 2015 and 1 January 2016 (both dates inclusive), join our mailing list to receive an email alert when the Primary One (P1) Registration Exercise webpage is updated with information for the 2021 P1 Registration Exercise in May.

你注册了MOE会给你发SMS提醒你的。

到时候互通有无吧。