To Nano..
Basically Forex brokers use standard time, which is EST. However, there are brokers that use GMT time. I once tried a demo account with a UK broker, with GMT+1, namely Varianse broker. I compared it with FX open broker, the difference was 2 hours.

For GMT+7 / WIB, I haven't found it yet, unless you trade with an Indonesian stock broker.
For trading or opening an account at Oanda broker, it's not much different from opening an account with other brokers. You just click open Account and follow the next steps by filling in your biodata, doing verification, then making a deposit.
Thanks.
@ Nano:
As far as I know, brokers that are currently operating and want to operate in Indonesia have their time in WIB around 4 or 5 hours after server time, because these brokers try to make their servers as close as possible to traders (users) for access speed.
The greater the time difference, the slower the access will be. If you want a server that is in GMT time, you might try brokers around the UK region that are not well known here.
For OANDA broker, as far as I know, clients from Indonesia will be redirected to its representation in Singapore (OANDA Asia Pacific Pte. Ltd) to avoid the FIFO regulations from NFA.
It should be noted that at OANDA the maximum leverage is only 1:50, deposits and withdrawals other than via wire transfer can be made via Paypal, and you can choose the trading platform, either Metatrader or fxTrade (OANDA's flagship platform).