"I understand that 晚会 means a party or a gathering but because of the character 晚 (as in 晚上), does it only refer to parties/gatherings that take place in the evening or at night?" YES! You are correct. And all the "晚会"sounds like a ceremony which is celebrated very grandly. "What if you're having a birthday party during lunch time on a weekend or an office party in the afternoon?" We can say"生日聚会" if a birthday party will be holding during lunch time on a weekend. "部门聚会" if an office party in the afternoon. Hope it helps. (●'◡'●)ﾉ♥

晚会 = evening gala or formal evening gatherings. We normally use the transliteration of the English loanword, "party".

Generally, 晚会 is a evening gathering or party with some stage entertainments or performances. , such as singing, dance, magic show, talk show, poem citing , etc.... The most well known is 春节晚会=春晚 晚宴 is an evening gathering or party with decent foods. 晚宴 or 晚会 is more formal. 聚会 is an informal party or gathering.

晚会 usually means parties that take place in the evening. You can use 聚会 instead. It's quite popular, and doesn't have a limitation of time.

晚会 is something more formal, usually we dont need to tell time on it we can just 生日聚会（生日派对 can be use too)，公司聚会 then you can decide the time yourself, just remember to tell them the time that they will be there. exemp: 小王你记得去我的生日派对，是今天下午三点。记得来！