Any advice on dividing lavender (Munstead, I think)?

I've got it interplanted with my grape hyacinths, which should be
coming up soon. (I'm in zone 5). I'm thinking of waiting until the
grape hyacinths die down, and then dividing the lavender. Right now
I've got 3 clumps of lavender, and I want to spread them out more
evenly, still interspersed with the grape hyacinths.

Does this make sense, or should I time it differently?

Irene