I would suggest keeping it the same or going even lower key -- skip the sleepovers / dates. Son can see BF around but no PDA and no introducing him as "BF" just yet. "A friend" is good enough for a 2.5 mos old dating partner. Maybe it's a litmus for the new dating partner -- cuz if he's going to kick up fuss because you also are a parent and have those kinds of obligations to meet... better to know it in the early days.
Son is visiting so could prioritize the SON and spending time with him. Both as a family (you + husband + son) and just you and him to strengthen that part of your polymath
relationships. Children count in it to me -- they may not be lovers, but child-parent rship is just as intense/intimate/close because they need so much guidance and care along the path to becoming adults themselves. 9 may be bright, but 9 is still only 9. YKWIM?
Could meet all the kid needs before hanging with grown ups who ought to get that dependent needs come first. Certainly ahead of grown up wants.