The silence between the shoot and the final delivery is when a client's anxiety climbs the most. They have no signal that the project is moving. The answer isn't to retouch faster, it's to give a first signal early, even a partial one.
The teaser: a small selection, fast
A few days after the shoot, send a small selection (10 to 30 files, as web previews, not necessarily fully retouched). The goal isn't to deliver the finished work, it's to show that the project exists and is moving forward.
That teaser is often enough to fully calm the wait: the client has something to picture, sometimes something to share, and waits comfortably for the rest.
The full gallery: the real delivery, with no speed pressure
Once the teaser is out, you retouch at your usual pace for the full delivery. You lose nothing on quality, you only gain on perception: the client no longer experiences the wait as a void, they experience it as a logical next step.
Two deliveries, two pages, one place to track
Technically, the simplest approach is to treat the teaser and the full gallery as two separate deliveries, each with its own page and its own expiry date. On xFer, you can create the two separately, under your brand, and see on each one whether the client opened and downloaded it.
Avoid mixing the two into a single delivery that quietly updates: the client then never knows whether they've seen everything or still have to wait. Two clear steps beat one ambiguous delivery.
In short
A quick teaser calms the wait, the full gallery arrives at your normal pace. Two separate, clearly dated deliveries beat a long silence followed by a single send.