Txindex=1: how to recognise the blockchain with this option?
You can check the debug logs (might require -debug flag) and see if it is indexing transactions:

$ tail -f ~/.bitcoin/debug.log


You can also try to get a transaction by txid, and if it returns transaction data, then the blockchain has been indexed for transactions (might have to wait for sync to complete):

$ bitcoin-cli getrawtransaction {txid}