AJ Bell also confirmed its two largest shareholders - co-founder and chief executive Andy Bell and Invesco Perpetual - would both retain "cornerstone shareholdings" after the IPO.
Past year the firm reported revenue of £75.6m, up from £64.5m in 2016, and pre-tax profit of £21.7m in 2017 versus £16.8m in 2016.
The company said it does not intend to raise new capital as part of the IPO due its financial strength, profitable business model and debt-free balance sheet.
The special offer for clients of AJ Bell allows them to buy the shares via the AJ Bell platform for one day before the shares will trade on the market and can be bought by customers of any platform.
Assets invested via the AJ Bell platform, which also serves the IFA market in the United Kingdom, have increased by 26% per year every year on average for the past five years.
Bell said an IPO is a "natural next step in our journey" and will boost future growth through raising the company's public profile.
He says: "We believe the outlook for our business is extremely positive".
Woodford sold its £40 million stake in AJ Bell shortly before the firm announced its intention to float on the market, according to the Financial Times. "The need for people to save and invest for their future has never been stronger and we are making it easier for them to do that". The remainder is split between other AJ Bell management (25%) and Seneca Investment Managers (3%).
Meanwhile, Sky News reported Woodford had been unable to participate in a £150 million fundraise at challenger bank Atom.
In order to participate in the early offer, customers must be a customer of AJ Bell's platform.
A Woodford Investment Management spokesperson said: "Neil has to make decisions about the allocation of capital all the time".