I would just individually assign it to that student.  When you are making the assignment this time, select only that student with a due date of your choosing.  It will be a separate column in your assignment report.

Two ways come to mind:

1. make a separate assignment for the latecomer

2. edit the due date of the original assignment to some point in the future. When you refresh the page, you should get a pop-up offering to add the student to the assignment.

What about the following scenario?...

1) I am preparing a class for many students for them to use while we're all on COVID-19 lockdown.

2) I fully expect the students to join over time -- not by any means "right away". (We're already locked down. I have no time to discuss joining with them in the classroom.)

3) I have a fairly large number of assignments to create (say some unit from Algebra 2), and I'd like those assignments to be available to every student as they join the class over time. But I don't want to wait, I want the assignments to be available "right away".

4) I expect 180 students to join over time. How do I manage this if I must manually update assignments (as per the comments above) every time a new student joins. Doing this 180 times doesn't seem to work well.

BOTTOM LINE QUESTION: Is there really no way for students to get "all" the assignments automatically when they join the class that's already "in progress"?

Hi, dhasan!  The best thing for you to do in this case is to make due dates sufficiently far away that they will happen after all students have joined (plus some time to complete them).  If a student joins a class that has active assignments, you will get a pop up next time you go to that class where you can choose to activate those assignments for the newly joined student(s).  So it isn't automatic, but it is pretty painless.  One click assigns them all.

I did this last summer.  I took charge of the summer review for students entering honors geometry.  I had students late entering the review "course" all summer.  But since the review sections were due in August, I could go on every few days just to see if there was anyone new to assign to.  Super easy.

Hope this helps!