Slow Growth. Need an opinion

I'm in day 19 Veg in a current culture system and 3 out of 4 clones are going incredibly slow.

My plan is to Veg out for 6 weeks. Should I scrap these ones and implent new clones?(going to delay me 2 weeks).

Or should I stick it out and hope for the best?

I would get more clones started just in case these don't come around.

As per HydroDan, May have to cut your losses and get a fresh bunch of clones from that healthier one. Also you don’t mention your PH, EC or light intensity.

What’s your humidity? It’s alway humidity ime, clones and early veg get that shit up 70-90rh