UK Citizenship Application for Child Born in UK, after both parents got ILR

[AtKap]

Hello,
Myself, my wife and daughter arrived in UK in MAY 2010 were on Tier2 ICT visa sponsored by my employer. We applied for ILR in Aug 2020. Three of us received the ILR in NOV 2020. My son who was born in UK, 8 years old now was on my Tier2 dependent visa, his visa has expiry date as on 1-Apr-2021.
As per the advice we did not apply for his ILR and understood that we can apply for his citizenship along with three of us, after we complete 1 year of ILR in NOV 2021. Some friend told me that we need to apply the citizenship for my son now as his dependent visa is already expired on 1-Apr-2021 and we should not wait.

I tried to search various posts but could not conclude on course of action.
1. Do i need to apply for my Son’s UK citizenship now or can wait until we all apply for it in Nov 2021?
2. If it should be applied now/separately, am i late already as his visa expired on 1-Apr-2021 and how to address this missed timeline?
3. Can you please guide me to relevance post, that suggests how to apply in such case?

Thanks in advance.

[CR001]

You could have applied for your UK Bron child as soon as you got ilr,there is no need to wait till you apply.

UK born children have an entitlement to register as British once either parent receives ilr.

You were already advised of this in July last year.

indefinite-leave-to-remain/tier2-ict-to ... l#p1937814

[vinny]

Agree with your friend and CR001. Your UK born son is entitled to register now. In a hostile environment, sooner is better than later.

[AtKap]

Thanks very much to you Vinny and CR001 for the prompt response. That was certainly a miss from my side. I have started the application online and hoping to submit it as soon as “Referee” details are sorted.
Thanks again.