Custom time filter

Is it on the cards to be able to create custom time filters. For example I'd like to monitor services in a region for which a "day" means 8:30am - 6:30pm

Another region would be 8.30am - 4.30 am the next day.

Can that be shown somehow?

Yes you can create date filters, and since Elasticsearch works in GMT you just have to create a filter based on the GMT Time you want

Check this out
You can also do things like "date-1h/h"

"constant_score": {
"filter": {
"range" : {
"born" : {
"gte": "2012-01-01",
"lte": "now",
"time_zone": "+1:00"

I mean in Kibana. I want to have my users be able to click on something that I can set up in the background.

Well in Kibana, you can set custome time's in the upper right corner and the way I handle is just build a Markdown Widget that links to the "Dashboard/search with the time frame included.

Example of a Dashboard link
This is what I have for a link,mode:quick,to:now))

Which is subset of this URL page (when loading the dashboard in kibana) Obviously you would change your URL to relect the timeframe you wanted.,mode:quick,to:now))&_a=(filters:!(),panels:!((col:1,id:DSG-SAR-PCPU,row:5,size_x:7,size_y:3,type:visualization),(col:8,id:DSG-SAR-PIDLE,row:1,size_x:5,size_y:4,type:visualization),(col:8,id:DSG-SAR-PIOWAIT,row:5,size_x:5,size_y:4,type:visualization),(col:1,id:DSG-SAR-PSYSTEM,row:8,size_x:7,size_y:4,type:visualization),(col:1,id:DSG-SAR-PUSER,row:1,size_x:7,size_y:4,type:visualization)),query:(query_string:(analyze_wildcard:!t,query:'*')),title:'DSG%20-%20SAR%20All')