No. Walmart will automatically update the promo pricing 24 hours before the start date of the Flash Deals week. Don’t submit promo price updates for approved items after the start of a campaign, unless instructed to do so. Changing price after the start of the campaign may result in losing the Flash Deals badge.
The promo price submitted by you and approved for Flash Deals will be compared with the promotional pricing offer set-up by you for the item and the holiday campaign offer (if any). The lowest promotional price between the available promotional prices will be presented to the customer. After the campaign ends, the price of your item will revert to the price it was before the campaign.

If you use a third-party Solution Provider, remove the approved items from automatic pricing updates at least one business day before the start of the campaign. 

You can find submitted deals and details on the Deals dashboard under Scheduled.  

After your initial submission, you can add or update your items before the submission deadline by navigating to the Deals dashboard and selecting Manage items.