No, you won't be charged for your existing portfolio. Portfolio under advisory will be calculated ONLY on those transactions that are made post your subscription.
Consider an investor had a portfolio of Rs. 1 Lacs before taking our plan subscription. After taking the plan, he/she further invest in MF schemes and bumps up their portfolio to Rs. 1.5 Lacs.
The net increase of Rs. 50,000 (Rs. 1.5Lac - Rs. 1 Lac) will be considered portfolio under advisory.