Query regarding T2 general dependent visa application

[Sv2018]

Hello members,

In case Main applicant apply alone:
If main applicant gets visa granted (30 days vignette) ,

is it possible for the dependent to apply after immediately on priority and enclose the main applicant visa approval copy and to travel with the main applicant
Or
Dependent has to wait till the main applicant enter the UK and get the BRP and start work and then dependent will apply to join him later?

Please help its urgent .
Thanks in advance

[Sv2018]

Dear moderators,

Awaiting for response for my queries.
Appreciate your help so far!

Thank you