How often will my ZSK be rollovered

dnssec
#1

I noticed that the DNSKEY rrset at zone apex is not signed online(on a fly), how to determine the inception time and the expire time of the RRSIG of the DNSKEY rrset?

Another question is that how often will my ZSK be rollovered and will the KSK be rollovered?

How often is ZSK rollovered
#2

I noticed that the DNSKEY rrset at zone apex is not signed online(on a fly), how to determine the inception time and the expire time of the RRSIG of the DNSKEY rrset?

Another question is that how often will my ZSK be rollovered and will the KSK be rollovered?