What strains are the plants they look mostly indica to me by the leaves. I can't really see if its ready the pics aren't clear enough need to see the trichs. Have a look at the hairs of the bud if they turned amber/red they are done.
You can chop of a lil bud to taste to see if its ready, let it dry then smoke it see what its like. Looks like they almost done, couple weeks or so.
Now u can buy some molasses and feed it to the plant this will put the weight on the buds and fill them out a bit. Give it a go get some molasses from supermarket add it to some water and then water the plants with it.
Evil