Now() As Record Id; What Record ID Schemes Are Fequently Employed Besides Date/time

I seek advice on using the value of NOW() as a record ID in an address book program. Question #1: Do Excel developers often use a record ID? Question #2: What record ID schemes are fequently employed besides date/time? I have decided to create an Excel address book as an exercise to increase my knowledge of VBA, and also as a useful application for work.

I realize that a record ID is not essential in Excel in the way that it is essential in Access, but I feel the need to have some unique ID associated with each address, so that I may have different worksheets, with data related to a given Contact, sort and manipulate it, if necessary, but have the record ID as a way to restore the relationship of rows to a given Contact, and also, as a handy way to examine the data in the date/time sequence in which it was entered. I have experimented with the following code, to assure myself that I can access the number returned by the NOW() function, manipulate it as a string, and format in various ways if necessary.

Dim n As Double
n = Now()
sn = Str(n)
p = InStr(sn, ".")
first = Left(sn, (p - 1))
l = Len(sn)
d = l - p
S = Mid(sn, (p + 1), d)....................