Canvas:SendWillRenderCanvases () running after Start() causing issues

In my settings menu I use a slider to control the volume. The SettingsMenu script's Start() function checks the PlayerPref to see what the player's volume is usually at. It then updates the UI slider value to match this preference and then sets the mixer's volume to this value as well. However, after the Start() function runs, the Canvas:SendWillRenderCanvases () runs. This function renders the SettingsMenu prefab, but it also updates the mixer's volume with the default value of the slider, due to it re-rendering the default slider after its value has already been set to the PlayerPref value. Is there anyway to force the Canvas:SendWillRenderCanvases () to run before Start()? Or have Start() wait until afterCanvas:SendWillRenderCanvases () runs to run?