It is always recommended to start seeking donations as soon as your event logistics are decided, ideally 6 months or more in advance, in order to give companies enough time to respond to your request. However, even last-minute requests on DonationMatch have a chance be approved. (We've seen events with less than a week get over $1k in last-minute goods and gift certificates. No promises, but it happens.)
One of the advantages to listing events earlier is to get in front of companies with items that are limited in quantity before they "run out." This is particularly true of brands who have specific quantities of products to distribute in a defined period of time.
Also, some companies respond only every 1-2 months in batches, so a shorter timeframe may mean missing that window.
Not all companies who use our system are visible, so you'll want to keep your event available to be discovered for as much time as possible.
In a nutshell, the sooner you post your event, the more chances you'll have to secure more items. We recommend listing events on DonationMatch as soon as you have all your critical details finalized (date, time, place, ticket price, audience demographics).