Double stick tape and a neck shim to raise the action enough to clear the pickup.
Seriously, there’s plenty of inexpensive templates available. Pattern follower bits from Woodcraft or online. Try the template over the pickup before you route. Not all jazz pickups or templates are the same.
Attach the template (really can use double stick tape here), use that to score the paint around the outer edges, remove most of the wood with a Forstner bit and drill press, route away.
You’ll probably want a long drill bit, called an aircraft bit, to drill the wire channel into the control cavity.