ACATS can be done electronically in IB Account Management.
Please log in to your IB Account Management via https://ndcdyn.interactivebrokers.com/sso/Login?RL=1. The username and password is the combination you created during your RIA master account application. If you do not remember your username, please contact firstname.lastname@example.org.
You can onboard your clients electronically via TradingFront and initiate ACATS in IB Account Management for both open accounts and pending accounts.
1) Click Transfer & Pay > Transfer Positions.
2) If you have multiple accounts or account partitions, or if you have a master account and you manage one or more client or sub-accounts, the Account Selector opens. Select the account you want to use for this transaction, or use the search function in the Account Selector to find the desired account. Click Continue to submit your account selection and close the Account Selector
3) In the Method list, select ACATS.
4) Enter all the required information.
Here are the full instructions from IB: https://www.interactivebrokers.com/en/software/am3/am.htm#am/funding/acatstransfers.htm
The processing time for each transfer request is fixed. In general, approved transfers complete within four to eight business days. Almost all transfers complete within ten business days. Each firm is required to perform certain steps at specific intervals in the process.