My dad applied for my 20 years old sister (f2a), should he apply for naturalization to be sure my sister does not age out?

[ChelleS 0]

I just help my dad petition today (January 10, 2020) for my sister who is turning 20 years old on Feb 29, 2020 (yes, leap year baby). I guess our dilemma is whether Dad should apply for Naturalization (which takes around 6 months to complete). According to my research, my sister's age will "freeze" by the time my dad becomes a citizen. Meaning to say, if dad receives his citizenship in July of this year, my sister's age will remain 20 year old and 5 months under the CSPA law.
However, it does seem that dad may does not need to apply for naturalization since according to the Visa Bulletin for January 2020, F-2a (FINAL ACTION Column) is current and the f2a (dates for filling column) visa is available for applicant from Nov. 1, 2019 and earlier. Nov 2019 was only 2 months ago from today.   The chances are, our priority date will be current within 4 months. This raises the question on whether Daddy needs to Naturalize.
We dont have priority dates yet because we just submitted the petition tonight. However, It looks like priority dates are set and sent within the first 2 weeks after submission.
I guess my following related questions are: (SCENARIOS)
1. If for example that we were to be provided a priority date of January 20, 2020, and then by March 1, 2020 (2 months from now), the bulletin says our priority date is "CURRENT,"  will her age be frozen at that time? Or do we have to wait for the approval date?
2. Does priority date becoming "CURRENT"  and  " i-130 APPROVAL" happen within the same time of each other. let's say within the same month? If yes, if my sister's priority date become current in march 01, 2020, and her approval date is  March 30, 2020,  will her CSPA age remain 20 years old? 
3. To my understanding, once a child's age "FREEZES," it doesnt matter whether her visa interview or actual flight and admission to the US happened past her 21st birthday. Is this correct? If for some reason her interview is set on March 30, 2021 (she would be over 21 by then), then she flies to the US in April 30, 2021 ( a month later), she will not be denied entry to the US, correct?

Thank you for your help.

[issea 43]

Is your sister currently inside or outside the US? If she is physically in the US with a legal status (such as student or work visa holder), your dad could also file the application for adjustment of status (AOS) besides the petition I-130, since F2A in Jan is still current (chart A). But it is not a good idea for a tourist visa holder to adjust the status. 

 

If she is outside the US, you've done all what you could do. In the meantime your dad could start the process of naturalization. If your dad's naturalization completes earlier than the I-130 approval or the interview for the immigrant visa or green card (depends on which route you are seeking: consulate processing or AOS), your sister's case can be upgraded to immediate relative category (minor child of USC) if by then she is under 21 years old defined by CSPA, or to F1 (adult child of USC). 

 

And the CSPA age is not what you understand in your post. It is the physical age minus the time throughout the pending I-130 (time interval between the PD and approval date). 

[Boiler 45,525]

Naturalise would be belt and braces, after all you never quite know what could happen.

Edited January 12, 2020 by Boiler