Most pitches aren't answered the first time, and almost never because the answer is no. Inboxes get buried and DM requests sit for weeks. The follow-up is where I'd expect a first deal to come from, not the first message.
The rhythm
About four days after the pitch, one short bump. Friendly, no new pressure. If you pitched by DM, this is the message that says you emailed too. That reads as organised. A third DM reads as pushy.
A week or so later, one more. Then stop. Two follow-ups, then move on. A brand that went quiet can still answer a new idea months from now, so leave well.
What a bump looks like
This is the first nudge Plug offers on a pitch's page, as it reads for the demo account's Everbright pitch (a demo brand):
Hi Everbright team — just floating my note back to the top of your inbox in case it got buried. Happy to answer any questions!
Short, no guilt, nothing new to decide. Give the second one a reason to exist: a clip you've filmed since, or a second idea for a different product. Never the same ask in new words.
The hard part is remembering
The wording is easy. Remembering is not. A pitch you can't see is a pitch you forget to follow up, and the follow-up was the part that worked. When you tap "I sent it", Plug sets the reminder, and the brand shows up as due on the day. Send the bump from your own inbox, then tap "I bumped them".