>> Do this mean that even in the DNS Registrar portal if we add a NS Server ( F5 IP Listerner ) there will be no effect on the SOA record since once the DNS traffic received to our F5 Listerner IP and the SOA indicated in the zone file of F5 is itself now it will process DNS traffic?
Yes, indeed.
Just to doublecheck, you are not working with DNSsec? as that will have further implications.
>> Answer: After stability period, let's say 1 or 3 days previous we will remove the previous NS Server define in the DNS Registrar and retain F5 Listener IP. Would this be ok?
Yes, sounds like a good plan. Once you get to that point, you can also remove the previous NS servers one at a time. Wait a few days (this should mean that more traffic goes to the F5 DNS), then remove the last old one. This gives you more time to fine-tune the system.