Investors could be thousands of pounds better off by being an ISA early bird compared to a last-minute ISA investor or even one who drip feeds money each month.

The research from Fidelity International looked at the investing habits of three hypothetical ISA investors – ‘Early Shirley’, ‘Monthly Monty’ and ‘Last Minute Lara’ – over the past decade and 20 years.

Here’s what it found:

Early Shirley invests her full ISA allowance into the FTSE All Share on 6 April each year and has done so over the past ten years. By being an ISA early bird, she would have seen her original investment of £149,160 grow to £155,836. Over 20 years, the returns are £303,452 on an original contribution of £219,560.

Monthly Monty also starts his investments at the start of the tax year, investing his full allowance in the FTSE All Share over the past decade. However, he prefers to split his full ISA allowance equally over twelve months. With this strategy, he would have seen his investment of £149,160 grow to £153,071. Over 20 years, the figures are £219,560 and £299,165 respectively.

Last Minute Lara waits until the very last day of each tax year (5 April) to invest her full ISA allowance into the FTSE All Share, and as such her £149,160 would be worth £146,912 after 10 years and £286,175 over 20 years.

Ed Monk, associate director for personal investing at Fidelity International, said this is certainly a more challenging start to the new tax year than on previous occasions. However, many investors will be looking to seed their investments this Spring to allow them with as much time to grow as possible.

He said: “Recent market volatility has undoubtedly taken its toll on most portfolios, as demonstrated by the marginal returns generated by our investors over 10 years. However, their performance over 20 years – creating the opportunity to increase returns by £80,000 – highlights the value of taking a long-term view.

“The important thing for investors to remember at the start of this tax year is that they have a choice. Those who have a lump sum available may want to invest in the coming weeks, to give themselves most time in the market.

“However, those who want to spread their investments throughout the year may want to establish a regular savings plan, and could still have the opportunity to build up almost an equally impressive pot as an Early Shirley. Staying focused in challenging conditions isn’t easy but can create the best opportunities to reach your goals.”

Fidelity revealed that one investor waited until the last second on 5 April to open a new account and invest their full ISA allowance of £20,000. On the other side, one investor contributed the full £20,000 allowance just three minutes into the new tax year.