Hi @Innov8tive,
Yes, you can undercoat over those areas now without creating problems later, provided it is done neatly. Due to the dark colour, I'd suggest grabbing some Dulux 1Step Prep Primer, Sealer & Undercoat and having the team at the Paint Desk tint it for you. This will make the primer a bit more of a grey colour than pure white, which helps when transitioning from dark colours to lighter colours. I would also suggest you apply two thin coats of primer, as one coat is unlikely to cover it fully.
Before applying anything, lightly sand the edges of the painted areas with a sanding sponge so there are no hard ridges. This prevents those edges from telegraphing through future coats. After sanding, wipe the wall down with sugar soap to remove dust and prepare the wall so the undercoat bonds properly.
You will need to apply the undercoat to the entire wall rather than just the coloured spots. Rolling only the patches can leave visible texture and sheen differences, whereas doing the full wall keeps everything uniform until you are ready for the final paint.
When you come back to complete the full job, treat the wall as normal. A light sand if needed, then apply your finish coats. The earlier undercoat will not affect adhesion or appearance as long as it was not applied too thickly.
Let me know what you think and if you have further questions, please don't hesitate to ask.
Jacob
