The verdict in three sentences
Delivering a parcel when the customer is out is one of e-commerce's most avoidable losses: every second attempt costs 1,000 to 2,500 FCFA. In 2026, having no slot pushes the failure rate to 15-22 %, while a slot chosen at checkout brings it down to 6-9 %. A day-before reminder by SMS or WhatsApp cuts absences by a further 40 %, and 55 to 70 % of customers happily pick a slot when offered one.
The hidden cost of slot-free deliveries
Without a slot, the courier arrives at random along the route and hits a closed door one time in five. Each failure triggers a return, a reschedule and a second trip. The table compares the setups.
| Setup | 2026 failure rate | 2nd-attempt cost | Customer satisfaction |
|---|---|---|---|
| No slot | 15-22 % | 1,000-2,500 FCFA | Low |
| Half-day slot | 9-13 % | 1,000-2,500 FCFA | Medium |
| 2 h slot | 6-9 % | 1,000-2,500 FCFA | Good |
| Slot + day-before reminder | 4-7 % | 1,000-2,500 FCFA | Very good |
| Slot + live confirmation | 3-6 % | 1,000-2,500 FCFA | Excellent |
The tighter and more confirmed the slot, the more the failure rate collapses. The day-before reminder is the most profitable lever: nearly free, it removes 40 % of absences.
The combined slot + reminder effect
Offering slots (morning, afternoon, evening, or 2 h windows) at checkout makes the customer accountable: they commit to a time when they will be present. The reminder the day before (SMS or WhatsApp) confirms the slot and allows rescheduling before failure.
| Step | No setup | With slot + reminder |
|---|---|---|
| 1st-attempt failure rate | 18 % | 6 % |
| Absences after day-before reminder | - | -40 % |
| Final failure rate | 18 % | ~4 % |
| 2nd attempts avoided / 100 parcels | 0 | 14 |
| Saving / 100 parcels (at 1,800 FCFA) | 0 | 25,200 FCFA |
On 100 parcels, moving from 18 % to 4 % failure avoids 14 second attempts, i.e. 25,200 FCFA saved for a near-zero reminder cost.
Checkout integration and the routing queue
Technically, checkout shows available slots based on the zone and the day's courier capacity. The chosen slot feeds directly into the courier's routing queue, which organises the run by time window. An automatic reminder goes out the day before (SMS/WhatsApp) with one-click rescheduling. You can also cap the number of orders per slot so a run does not overload. Kolonell builds slots, reminders and the routing queue into the mobile Wave/Orange Money checkout.
Mini case study
Moussa runs an electronics store in Abidjan: 600 parcels/month, currently slot-free, 18 % failure (108 failures), average 2nd-attempt cost 1,800 FCFA = 194,400 FCFA of monthly losses.
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He turns on 2 h slots + a day-before reminder. Failure drops to 5 %, i.e. 30 failures versus 108. He avoids 78 second attempts x 1,800 = 140,400 FCFA saved per month. Reminder cost (bulk SMS/WhatsApp) stays under 15,000 FCFA/month. Net gain: ~125,000 FCFA per month, before counting higher customer satisfaction.
FAQ
What slot granularity should I choose?
2 h windows offer the best failure/satisfaction ratio (6-9 % failure). Half-days are simpler to run but leave failure at 9-13 %. Start with half-days and refine if volume justifies it.
Is the day-before reminder really effective?
Yes: it cuts absences by about 40 % at near-zero cost. It is the best cost/benefit ratio in the whole delivery chain, especially on WhatsApp where open rates are very high.
How many customers pick a slot?
Between 55 and 70 % when clearly offered at checkout. The rest accept a default slot. The simpler the interface, the higher the pick rate.
Do slots complicate courier routes?
On the contrary: by grouping parcels by time window and zone, the routing queue optimises the run. You just need to cap parcels per slot to avoid overload.
Can I combine slots and delivery zones?
Yes. Available slots can depend on the zone (out-of-town served only at certain slots), optimising both cost and success rate.
Let's talk about your project. We integrate slots, day-before reminders and a routing queue into your checkout to cut failed deliveries. WhatsApp +221 77 596 93 33.
Mohamed Bah
Fondateur, Kolonell
Passionate about digital and entrepreneurship in Africa, Mohamed has been helping Sénégalese businesses with their digital transformation since 2020. Founder of Kolonell, he believes every SME deserves a professional and accessible online présence.
