What happens if you don't harvest for a few weeks later? Will they get bigger?
There is a natural cycle that cannabis follows. For flowering, it goes like this: Transition, Bloom, Bud Swell, and Ripen. Each of these are distinct phases within the flowering cycle.
If you go past the ripen stage, the plant will make an attempt to revegetate. The buds will start to elongate and get leaves. Potency goes down.
Every variety is different, but in general for an eight week variety: transition lasts for 2 weeks, bloom lasts for 4 weeks, and bud swell lasts for 2 weeks. Ripen is the time I put in at the end waiting for the trichs to swell. Sometimes more than eight weeks total, sometimes less.
I have also grown quite a few varieties recently and I have noted that the color of the trichs isn't the best indicator. Perfect harvest time is best determined with a 40 or 60 x loupe by looking at the actual heads of the trichs - and ignoring the colors.
When most of the heads have a large balloon attached on top - you are at the peak of cannabinoid production. That is, IMO, the best time to harvest. Sometimes they are clear when this happens (some sativas)... sometimes they are all milky when this happens. Sometimes a mixture of clear, milky, and amber.
If you continue to let it go till there is lots of amber.... a lot of the balloons will become brittle and fall off.
I don't ask that you trust me on this - get yourself a 40 or preferably a 60x loupe and watch the changes for yourself...
. panty, in regards to your question, they appear a little young to be flowering fully, like chitown said, it can take certain strains upwards of 11 weeks in flower before you see any "major" growth. but they are looking great so far, just be patient and you will have buds before you know it