How do you deal with changes in time period

[Monkeytree]

So I am writing a historical novel which flips between modern day and past era. The modern day is written in first person and I find it easier to deal with any time lapses - there aren't massive ones anyway and the story flows well
BUT
the past era I'm find a nightmare to deal with time lapses (I need to fast forward a few years within a single chapter ideally when somebody life changes very much for the worse) and it is written in the third person, I really don't know how to deal with this and write it well. I feel I need to condense this particular part of the story into one chapter to maintain pace but don't know how to phase in the time lapses. Any advice please?

My last novel had ten(ish) scenes per chapter.
The first scene of each chapter was always the historical narrative. It had its own voice and time that was very different to the other present day scenes.

However, I agreed with my editor that we would still preface each historical scene with the date to immediately ground the reader. It might have been overkill, but we decided that readers who didn't need the heads up would just skip the date and it might help anyone who was a bit lost.

Voice and tone...

Thanks Getahaircut will take your comments on board x