It's not prohibited to celebrate things during the first 10 days of Muharram, but it is better not to celebrate out of respect for Imam Husayn.
If one considers it necessary to celebrate something (for instance, a wedding of a relative who is not Muslim), it is good to be moderate and more serious during the celebrations or spend a limited amount of time on celebrations, rather than being extremely celebratory.
However, these are not requirements; rather, it is simply a matter of respect and honoring the seriousness days. Generally, people who do commemorate the martyrdom of Imam Husayn over the first 10 days of Muharram do not want to engage in celebrations, anyway. But it is understandable that life happens, and sometimes other things occur during these days.
So it is your own decision.
It is very bad form to have celebrations on Ashura itself, and I personally would avoid that not only out of respect for Imam Husayn, but out of fear of divine displeasure.
In some Sunni-majority regions, for historical reasons, it is customary to celebrate Ashura in a happy way as a holiday, and while I find that deeply distasteful, I do understand that this is their history and custom and they are honoring it in the way they are used to honoring it, and are not intending any disrespect towards him.
