Hello customer service, can I use today (April 8, 2018) version of ZCash4Win v1.0.12 for transactions? ZCash4Win is running, the balance is displayed correctly.
Yes. You can use this to send transactions up until the Overwinter hard fork (for which no date is currently set, but likely late June).
As per this post https://blog.z.cash/release-cycle-update/ you will need the
disabledeprecation=1.0.12 flag - but I guess you must already have this if it’s running.