That's a pretty impressive seedling set-up you have there! Never tried growing lavender from seed... that's impressive; we've only ever done cuttings.
Waiting for the last frost here, too... probably a couple of weeks. Pacific Northwest weather can be pretty unpredictable, although we're technically past "average last frost" it can still happen until about April 10th.
Your little pine trees are inspiring me to go dig up some of our tiny "volunteers" around the property and nurture them in pots till they are a bit hardier.
RE: Waiting for the end of frost