Try introducing your new brand while the old one still exists… If i were in your place I would use the Pareto Principle… Identify the 20% of products that brings in 80% of my revenue and rebrand them… While the 80% of the products that bring in 20% would be under the same old brand name… So that my existing customers don’t feel it’s a complete revamp and it appears more of a smooth transition…

Assuming you just want to change the logo while the offering and propositions stay the same…

Rookie Cookie… Sell the story of you how someone who is passionate about cookies and baking is entering the market diluted with big brands