A slow or a hot rental market will have the biggest impact on how long it takes to get a tenant.
If the rental market is hot, finding a tenant will be faster. And vice versa.
This is largely out of your control but it's a major factor.
Similarly, if a tenant's application falls through, you might have to start the process again.
On top of that, existing tenants can slow the process down in both directions. A new tenant with long notice periods can delay move-ins. Whereas existing tenants need 48 hours' notice to allow new tenants to come in to view the property.
Sometimes tenanted properties can take a bit longer to rent because of access restrictions from the current tenant. It's time-consuming having to work around work and family schedules compared to an empty property.
And don't forget, a property filled with mess and packing boxes from a moving tenant, can make your property a little less desirable looking.
But sometimes property investors shoot themselves in the foot. They get an application. Then they wait for a better one to come along.
The issue is that the rental market moves fast.
Tenants aren't just applying for your property. They're applying for other properties too. So, if you are slow to approve a tenant … another property investor might snap them up instead.
If you're flexible on move-in dates too (better to wait a few days for the right tenant, than an extended vacancy), and allow pets ... you'll often find getting a tenant much easier.