Plan for about 10 to 16 weeks from kickoff to launch for a custom-design Plus build with a large catalogue and one ERP integration. Published ranges for custom-design Plus builds run 8 to 16 weeks, and slow design approval or an ERP with poor documentation pushes you toward 20. Give stakeholders a range, not a single date.
The two most common causes of slip are design approvals and integration access. Both are mostly people waiting on people, which is why clear ownership shortens projects. If a build is already late, read our guide on whether to push through or switch agency.
Phase-by-phase timeline
Weeks per phase, with the overlaps that keep the total down.
| Phase | Weeks | What happens |
| Discovery and planning | 1 to 2 | Requirements, analytics, URL mapping and integration scoping |
| Design | 2 to 4 | Wireframes, desktop and mobile UI and page templates |
| Development | 3 to 8 | Theme build, configuration and custom features |
| ERP integration | 1 to 4 | Runs alongside development once API access exists |
| Content and data | 1 to 2 | Product, page and SEO data, prepared in parallel |
| Testing and QA | 1 to 2 | Cross-browser, checkout, performance and SEO checks |
| Launch | 1 | DNS, redirects, tracking checks and soft launch |
A realistic total range
Use a range and explain what moves it.
- Standard custom builds run about 6 to 10 weeks, and Plus builds with bespoke design and several approval rounds run 8 to 16 weeks.
- Add time for the ERP integration. A task quoted at two days can take two weeks when an API has undocumented quirks.
- Planning range for this scope: 10 to 16 weeks, up to about 20 if approvals or access slip.
- First-time projects often underestimate by 30 to 50 percent.
The two things that cause slip
Fix these early and most of the schedule risk goes away.
What happens: slow feedback turns a ten-week project into a fifteen-week one.
Fix: name one decision-maker, set 48-hour review windows and agree wireframes before visual design.
What happens: sandbox credentials, API documentation and a named ERP contact arrive late, so integration starts late.
Fix: request them in discovery and add buffer for undocumented behavior.
What runs in parallel
Overlap these workstreams and the calendar shrinks without extra risk.
- Content preparation and development.
- Data prep, content writing and redirect mapping.
- Copywriter and photographer sourcing, started in discovery.
- ERP integration and theme development, once access exists.
How to compress safely
Speed comes from preparation, not from skipping steps.
Brands that arrive with content ready can cut about 2 to 4 weeks from a typical build.
Projects with clear ownership launch about 30 to 40 percent faster than projects run by committee.
Log new requests for a later phase instead of adding them mid-build.
Fix product and customer data before the project clock starts.
Compressing further usually means spending more on parallel teams or scoping less.
Builds that combined catalog, design and integration
Data migration to Plus, tiered pricing by customer group, account-based purchasing and a B2B portal. The store removed more than 25 WooCommerce plugins, and support calls dropped by more than 80 percent.
Read more: our HFF Custom Rods Shopify Plus case study
B2B data migrated with a custom app, region-specific catalogs for UK and EU VAT, and an enhanced NetSuite integration for B2B and B2C orders.
Read more: our Easilocks Shopify Plus case study
Share your catalogue size, design status and ERP, and our Shopify Plus development agency team will give you a phase-by-phase plan with a realistic range.
Frequently Asked Questions
Published ranges for custom-design Plus builds run 8 to 16 weeks. With a large catalogue and an ERP integration, plan for about 10 to 16 weeks, and up to 20 if approvals or access slip.
Slow design approvals and late ERP access. Content that is not ready, scope added mid-build and unclear ownership also cause slips.
Yes, once API access and documentation exist. It runs alongside theme development, which is why requesting sandbox access in discovery matters. Our guide to syncing ERP inventory with an online store covers the data side.
Published guidance puts mid-market catalogues of 500 to 5,000 SKUs at 4 to 8 weeks with standard integrations. Custom design and ERP work extend that.
Prepare content and data before kickoff, name one decision-maker, freeze scope and keep feedback windows short. Compressing further usually means spending more or scoping less. Our Shopify Plus development agency team plans builds this way.
