Which systems should you integrate during a CRM implementation, and which can wait?
Integrate what blocks a daily workflow. Everything else belongs in phase two.
In phase one, integrate only the systems that block somebody's daily workflow if they are not connected. Everything else goes to phase two, after the data model has stopped moving. Integration scope is the most common reason a CRM go live date slips, and it is the easiest one to control.
The triage rule
For each system, ask one question: on day one after launch, does someone have to stop what they are doing and go to another tool to finish a normal task? If yes, it is phase one. If the answer is "it would be nice to see that data in here," it is phase two.
Phase one almost always includes email and calendar, your website forms, and your calling or texting tool. Those are the daily workflow. It usually includes e-commerce if you sell online, because order data drives service and marketing from the first day. For Shopify we use Unific, which handles the product and order side properly rather than syncing a subset.
Phase two is most of the rest: the ERP feed, billing, the support tool, the proposal and e-signature system, the webinar platform, the data warehouse. Useful, not blocking. PandaDoc for e-signature is a good example of a phase two connection that becomes obvious once the deal process is stable.
Why order matters more than the list
An integration is written against your properties. Build it in week three, rename three properties in week five during migration cleanup, and you pay for the integration twice. Worse, a live integration makes the data model harder to change, because now something else depends on every field you wanted to fix. Let the model settle first.
The same logic applies to direction. Before you connect anything, write down which system owns each shared field. The ERP owns the invoice. The CRM owns the contact. Without that decision the integration becomes a loop where two systems overwrite each other and nobody can tell which value is current.
Native first, custom when you have to
Use a supported native integration when one exists and does what you need. It is cheaper, someone else maintains it, and it survives platform updates. Build custom when the native version is missing a field you genuinely need, when the system is industry specific, or when the logic is more than a field to field sync. The difference matters more than people expect. We build the custom side too: see our integration services.
Related: What systems can LevelUp Digital integrate? | Can you connect HubSpot to our ERP? | How long does a custom integration project take?