Trailing stoploss

I am planning to apply trailing stop loss on my positions.

For new buys, I can place a stop-loss at 20% but every week I have to check the price.

I have placed SL using GTT and if the trigger price is more than 21% I will adjust it to 20% daily.

Example:

Buy Price: 100

SL placed during buy: 80

Week1:

Price of stock: 85

SL for the week: 68

SL will not change in GTT order since 60<80.

SL remains 80

Week2:

Price of stock: 102

SL for the week: 81.6

SL will change in GTT order since 81.6>80

The new SL order is 81.6

Week3:

Price of stock: 125

SL for the week: 100

SL will change in GTT order since 100>81.6

The new SL order is 100

Week4:

Price of stock: 150

SL for the Week: 120

SL will change in GTT order since 120>100

The new SL order is 120

Week5:

Price of stock: 180

SL for the Week: 144

SL will change in GTT order since 144>120

The new SL order is 144

Week6:

Price of stock: 145

SL for the week: 116

SL will not change in GTT order since 116<144.

SL remains 144

Week7:

Price of stock: 190

SL for the Week: 152

SL will change in GTT order since 152>144

The new SL order is 152

Week8:

Price of stock: 150

SL for the Week: 120

SL will not change in GTT order since 120<152.

The price of the stock is 150 < SL so the stock is sold.