Introducing older rescue to resident kitten

[dinosaursgorawrrr]

Hi,
I currently have 8 month old Dcat and since bringing him home we have been on a waiting list with a rescue to hopefully get him a friend as he just wants to play all day and the dogs are only happy to play for so long before the get bored and wander off.

The rescue have a gorgeous boy that looks like he will fit in amazingly and his personality is almost identical. The only difference is he's between 1 year and 18 months old so possibly nearly 10 months older than resident kitten.

The rescue are happy to let them meet the same day but should I try segregating them for the first few days anyway? Dkittens desperate to play with the neighbours cats so I'm hoping he will love having a playmate but worried it could all go wrong 😥

Has anyone introduced a slightly older kitten/cat to a younger resident kitten? I can only find out about people doing the opposite which is what we had planned but this cat needs a home and does seem the perfect fit. We have room to separate them if needed along with baby gates.
Any helps appreciated 😄

New cat is home 🏡 He had a accident in his carrier on the way home so ended up with a bath. Unfortunately I was also covered in cat 💩 so both cats met briefly while I had the bathroom door open.
New cat purrs at resident kitten and could not care less if he's in the room..intact he hasn't stopped purring since he got home.
RK is curious and want to see NC but when NC moves he hisses and runs away. I have felliway coming tomorrow so hopefully that will help. NC wants to play but RK is going to take some persuading..until then NC is in his own room with DS (10) so that interactions can be monitored.
Is there anything I should/shouldn't be doing? The rescue said to just leave them to it once NC knows where his litter tray is but the Internet says to keep them apart.

Picture for tax 😅