travel together...

[dealsone]

me+wife+child got our immigration visa on 14april18 (medical was on 20march18)
wife is principal applicant

1.
is it mandatory for ALL 3 of us to travel *together* (& reach usa) on the same date & flight (before 18sept18)
or
can wife & child travel(reach usa) around 20july18 & i travel(reach usa) alone, anydate AFTER 20july18 but BEFORE 2018sep18.

2.
we are supposed to remit $ 660 (220X3) as green card/immigration fees
do we have to pay here in india BEFORE leaving for usa
or
we could even pay after landing in usa

tia

[scientist2016]

me+wife+child got our immigration visa on 14april18 (medical was on 20march18)
wife is principal applicant

1.
is it mandatory for ALL 3 of us to travel *together* (& reach usa) on the same date & flight (before 18sept18)
or
can wife & child travel(reach usa) around 20july18 & i travel(reach usa) alone, anydate AFTER 20july18 but BEFORE 2018sep18.

2.
we are supposed to remit $ 660 (220X3) as green card/immigration fees
do we have to pay here in india BEFORE leaving for usa
or
we could even pay after landing in usa

tia

1. No, you can travel separately.
2. Your choice, but your GC issuance process will commence only after the payment of the fee, or entry in to the US, whichever is the latest.