Get it Live
We see it all the time, a mountain is created out of implementing a piece of software that works out of the box. Customize your forms, set up your accounts and items, turn the thing on and start processing transactions.
If need be, leave your old system running and run parallel paths until the systems mirror, but trying to do a hard cutover without proper testing and acceptance is fraught with errors, and what we typically see is long drawn out implementation cycles that last months, even years, instead of weeks.
Our first time implementing Netsuite, we went live from a laptop while on vacation in 5 days. The company was running hundreds of transactions daily and at a run rate north of $1M a month.
Netsuite is no different than any other software. Start with a Minimum Viable Product, and rapidly iterate using an Agile Methodology. Get to Hello World first.
The approach is even more important depending on the complexity of the system. Extremely complex implementations should be approached with an Adjacent Path methodology.