Of course there is no straight answer for this.
In line with the Wealthsimple way of investing, we should always control what can be controlled. You should contribute into a pension as early as possible, and contribute amounts you are sure you will not need to access before your retirement age.
Often, we find the neatest and most successful way to amass pension savings is by setting up a monthly direct debit into your scheme. A rough rule of thumb would be to halve the age at which you begin contributing into a Pension. This number represents the percentage of your salary which should be invested into a pension per annum, and it shows the benefit of starting early!