Baby wants to sit, is it safe?

JKR

My 5 month old is always wanting to sit up since she was a month old. But I started letting her sit with support for a few minutes at a time only after she turned 4 months. Now that she's 5 months old, for how long can she be made to safely sit supported in my lap at a single stretch? I've been told by visiting aunts that it's bad for her spine if its for more than 2-3 minutes at a time. Any truth in that?