So I guess he is not in preschool.
Does he nap in the afternoon?
If your son is tired, it might really be hard to keep him up. What time will he have to stay up until, until your Husband gets home... and how long after that will he still be up, to play with Husband? By then, then what time is it that he will be going to bed?
Keep in mind...that if you alter his usual bedtime, in order to stay up later for Daddy... it might be VERY VERY hard, to get him back... to his normal bedtime. Not all kids, will adjust.
And, he may NEVER, again go to bed early at his usual time... if you make his bed time later for only 4-8 weeks, and he may never want to go to bed at his usual regular bedtime, ever again. After this. And he may then just get used to going to bed late. And it will backfire. Because, then when 4-8 weeks is over, he will NOT want to go to bed at his usual regular time. Because he will be used to, the late, routine.
Is Husband wanting him, to stay up later, in order to wait for him to come home and then play once he does get home??? Does... your Husband want you and your son to do that? Will your Husband, be all ready to play with son, when he gets home from those night meetings? He'd need to eat dinner too, wind down, etc., and then that will make the timing of things later and later. And then play with son, for how long, and what time will son be going to bed? After all that?
If you keep son up later, and have evening activities for him in order to keep him up later for Daddy... it might actually make him too tired and sleepy, to then have to stay up later, to wait for Daddy to come home, later. And then stay up later for Daddy.
Tired over tired kids, get fussy and cranky.
If your son has to stay up later, but gets fussy and cranky by the time Daddy gets home later, then what?
If it were me, I would just keep my child's bedtime the same. Despite Daddy coming home later.
For me personally, my kids getting adequate sleep, and sleeping when their usual bedtime is and them being tired at that time and going to bed, is more important.
And in fact, when my kids were younger and my Husband worked late a lot, I just kept my kids' bedtimes, the same. I was with my kids, solo, most of the time. Their sleep schedules were important.
Per my kids: IF they are doing a lot of activity at night, prior to bed, then I had to get them WOUND down, again... in order to get them keyed down for bed. And that took like 1 hour, down time, prior to bed, to get them keyed down, for bedtime.
IF your son is having evening activities... he might get sleepy/tired before Daddy actually comes home. Then he'll need to stay up longer, to see/play with Daddy. So that is 2... activity periods, for him, at night, before bed. Then, he'd need to key down, before bed, which would be later than he is used to. And who knows how that will affect him. Especially if he is regular about his sleep times.
That would not work, for my kids, when they were that age. When my kids are tired, they are tired and go to bed. Sure I could make them stay up later if I had to, but that was not something I wanted to do.
Remember: It ALSO... affects the child the NEXT DAY. Keep that in mind. They will either still wake up early as usual (even if they did go to bed late the night before), or they will sleep in longer, the next morning.
So think about that.
All the times that my Husband worked late, and my kids did not see him, they were fine. I would explain that Daddy was working late. But we'd all see each other the next morning, before my Husband went to work. And he'd make extra time, in the mornings, to spend with them... before going to work.
For me and my Husband, our kids going to bed at their regular times and getting adequate sleep, was important. More so than having them stay up later at night, until he came home from work. There were many times my Husband, was even later in getting home at night than he thought he would, because, work and meetings and trouble shooting at work, would at times, make his coming home time, later.