[GNC] Starting from scratch

[Clint Chaplin]

Hi, (soon to be) new user here.  I have almost 40 years of transactions, in
programs that are incapable of exporting, so I'll have to start entering
them in manually.

What strategies have people used in the past when starting up GnuCash?  I
sorta understand for normal "cash" transactions I can probably just start
entering in transactions for the current year, but can the starting balance
be changed as I work my way backwards?

For stocks and mutual funds, should I start at the beginning and work my
way forward?  I'm not sure just how clean it is to start entering current
transactions and then work my way backwards, especially given that account
fees are taken FIFO from the first purchase in the mutual fund.

Mortgage may be interesting, or simple.

BTW, USA user.

Any advice would be greatly appreciated.  Thank you.
-- 
Clint (JOATMON) Chaplin