How to estimate reindexing time?
As you have 200 index, it would take longer than a vacuum. A reindex always depends on your OI. It seemed that it would take more than an hour.

What I would suggest is:


get rid of some indexes. 200 for 100 columns makes no sense. See how many of the l those you use 90% of the time.

1.1. The other queries would find their path along other indexes

1.2. Your record takes more time recording indexes than rows, I that should be slowing down your night update
You could reindex the indexes the you use the most

2.1. Use REINDEX INDEX index_name;

2.2. If you can run some reindex in parallel, it would make better use of your server cores