Complex sentence: The first Red Nose Day (RND) was held on 5 February 1988, when it was launched as a National Day of Comedy, and since then they have been on the second or third Friday in March.
Split into simpler sentences: The first Red Nose Day (RND) was held on 5 February 1988, when it was launched as a National Day of Comedy. They have been held on the second or third Friday in March.