Honestly, skip it. At 5 packages with sequential builds you're not hitting the wall yet. I've seen teams burn time wrestling Turborepo config for problems that don't exist.
The real reason to switch: when you hit CI bottlenecks or developers are waiting on builds constantly. That's probably 15-20+ packages or complex dependency graphs. Right now you're not there.
If build time becomes an issue, just add npm run build --workspace=package-name to your CI and build in parallel. Takes five minutes, zero dependencies. Cross that bridge when you get there.