Finishing / Filling base of stair spindles - choices choices

[not_an_exit]

Hi
I've just had some new stairs put in. The spindles need to be painted, but I have a load of gaps around the base of every spindle (see photos). I am thinking about how best to finish this area. I could fill the little gaps with polyfilla, wood filler, or decorators caulk. Or leave as is, paint it and hope for the best. Or something else that I haven't thought about. Any ideas about the best solution?
Thanks for any help!

[not_an_exit]

Thanks for those replies both. Seems like I should try the undercoat solution first (easier), and if that doesn't work then resort to some sort of filler. Thanks for the help!