GE 15086 7-day programmable timer will not work for 3-way switching.
It is possible to wire GE timer in place of a 3-way if you tape the other switch in one position.
Add a comment if you want help with that wiring.
There are several 7-day programmable timers that can be wired for 3-way. Each of these is wired slightly differently, and you have to look at wiring diagrams carefully. But they are completely do-able.
Links below go to pages that show manuals and information.Aube
Aube T-1070 7 events
Aube T-1073 21 eventsUPM
ETW193 20 events
ST01C 40 events
Intermatic EJ500 40 events
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