In general, if and when they answer the DV, they will give you some time to contact them to work out possible payment options, etc. Or not. In general, they will wait at least a few weeks before they file, but there are no guarantees.
I remember once getting a letter demanding I file in arbitration within 30 days or else they would file suit, so I did.
That is why it is probably best to file as soon as you hear from them.
The opinions on DV letters have changed dramatically over the years.
When I first started on this and other forums, the thought was to make the DV letter very complicated.
Now, the idea is to make the DV letter as simple as possible.
Dear Evil Debt Collectors,
I dispute this debt and demand validation of this debt.
I hereby invoke the arbitration clause of the underlying contract, and demand that all disputes be handled by arbitration.
I revoke any permissions to call my cell phone.
Please make any communications exclusively by US Mail.
Or, the even simpler:
I dispute this debt.