Aegon has acknowledged teething problems with its new platform but added most of the services are working properly.
The provider spent the recent bank holiday weekend upgrading the platform and integrating the Cofunds platform it acquired in 2016.
A spokesman for Aegon said: "We had over 2,700 users activate their accounts to the upgraded service on Tuesday (8 May), exceeding our expectations.
"It was also good to see new business being placed and customers trading. After all the preparation and testing, we are encouraged that all our core services are working as they should."
The Aegon Platform, serving what was the Cofunds retail adviser business, will deliver a wider fund range, a new integrated pension and a number of new paperless and signatureless services as part of modernising the platform proposition.
For launch Aegon prioritised services on the platform that allow advisers to transact, service and grow the value of their existing customers and ensure adviser charges are secured.
Over the coming weeks there will be further functionality improvements including more paperless/signatureless services, improved services for new customers and the launch of ETFs, investments trusts and share trading.
This is all part of an ongoing programme to progressively build greater functionality in a bid to differentiate the platform and make it the market leading intermediated platform.
But a spokesman for Aegon admitted the work has thrown up some issues.
He said: "We recognise that it will take time for advisers to get used to some elements of the new platform and where advisers have flagged issues, we are working quickly to address them."
His comments come after several advisers contacted FTAdviser to say their attempts to use the platform have been met by "chaos".
One adviser, who wished to remain anonymous, said: "So far it is a step backwards. Our experience is that it is chaos at the moment.
"Staff are not trained up properly to help with our queries.
"We are being told to use Trustnet for fund performance as there is no function for portfolio reporting. Very disappointed at the moment."
Another adviser, who wished to remain anonymous, said: "I logged in today for the first time to complete two tasks. First was for an existing client who wanted an update on the performance of their Isa. I can no longer see what he originally invested (book cost) so bit difficult to calculate this since inception or over the years.
"Second is for a client who has just transferred her pension over to Aegon and is about to go into drawdown for an income. Looks like the transfer was completed today and monies have just appeared currently sat in cash. Called for some hand holding on how to get this invested into the correct funds.
"Appears this is one of the things that can't be done online and needs to be paper-based.