I-485 filing - with or with out dependents

[Nexus5]

Hi. 

I (principal applicant) am ready to file I-485. But I have to wait for 1 or 2 months to get 
birth certificate related documents for my wife. 

Can I file my I-485 immediately and file my dependents' (wife and kid) I-485 separately? 

Their applications will trail mine by 1 or 2 months. 

Is there any compelling advantage of filing together? 
What will be their status if my application gets approved first? 

I am in H1B and my wife and kid are in H4. My wife's H4 EAD is pending for approval. 

thanks a lot for any answers.. 

regards, 
Nexus5

[pontevecchio]

File the AOS for all three. You do have the child's BC? They will send an RFE for your wife's BC.