Integrating 5 day and 2 day old chicks

[MamaMaK]

New chicken mama here. Last Saturday, we brought 4 chicks home. Wanted more but the other breed I wanted hadn't arrived yet. Yesterday, 4 days later, I brought home 4 more chicks.
The clerk at the feed store said not to put them directly in together, didn't give a timeline, but in a FB group I'm in, I was told I can after a few days when the new chicks settle in.
When can I allow them to be together safely and what behavior should I expect when I do?

*Update: removed the barrier and stayed with them for a while. No aggression shown. They seem to be just fine together. Also, this was taken after cleaning the brooder so the thermometer is still adjusting.

 

[Poodlemum]

I’ve never had that trouble, they should be fine! That’s such a small difference

 

[MamaMaK]

I’ve never had that trouble, they should be fine! That’s such a small difference

Thank you. I'm new to this and don't want their welfare to be jeopardized by my ignorance.

 

[3KillerBs]

It shouldn't be a problem unless there is a HUGE disparity in size.

 

[MamaMaK]

It shouldn't be a problem unless there is a HUGE disparity in size.

There isn't. I put them together a few hours ago. I was ready to rescue if there was aggression but they just seemed curious and started eating and drinking together.