Riders are all different, some wear jackets at 55-60F, others wait until 40F. So, keep track of what works for you.

The trickiest part is rides that warm up during the morning, or cool down at sunset. It's complicated to pick the right layers.

I always feel warmer in the spring after adapting to cold winter weather, so I'll go maybe 5-8F colder with the same layers.

All these layers are wicking. I like the more expensive base layers from REI, they have a smooth surface and are easy to add another layer over.

I'll sometimes use 3 thin longsleeve base layers. Each layer doesn't block wind by itself, but with 3, I stay warm in the wind.

For rides that might get cold or start cold, I've used the newspaper vest idea. I have some of the blank newsprint thickness of packing paper, for shipping in cardboard boxes. I can fold up a chest sized piece and bring it if it gets too cold. It's surprisingly warm in the wind.
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Stuff I like:

I have a PI convertible jacket, with zip-off sleeves on a shoulder yoke. There's a big vent under the yoke in back, so I get great airflow if I unzip the front. Nice on climbs. It's a good windblocking vest with the sleeves unzipped and stowed in the back pocket. It's expensive, but worth it.

The unlined jacket is good down to 30F with a selection of thin layers under it. No need for a lined jacket.

I have thin, unlined tights that go over bike shorts. I need a new pair, and the thin fabric ones are hard to find.
And I have a medium weight windblocking tight for under 50F.

A selection of gloves, from REI very thin glove liners--that fit under fingerless gloves, to windblocking fleece, to goretex shell gloves with various liners. (My fingers get cold easily)

A cheap fleece neck gaiter to block the wind from my chin and neck at 45F or below.

A couple of skullcaps in thin and heavy weights.