Claiming it in one year must be a good choice as I’m not much of a tax planner. Consider your OTC is lower than 100% ITC, then it isn’t better to claim it over the periods at a rapid rate because you want to sell the asset before it’s useful life.
Claim it as soon as purchased and invoice & capital goods received received. Entry on sale will be done as normal sale entry is done along with depreciation and profit and loss on sale of asset. For GST value will have to be determined as per provisions of law.
There is no method prescribed in to claim ITC for capital goods in 5Years. Actually you have been confused , it's when capital goods are used for making both taxable & Exempted supply the quantum of credit on such capital goods is restricted to the credit attributable to Taxable supply. So in term of provision of rule 43 of CGST the reversal of credit is required for the portion of credit which is attributed to Exempted supply & it needs to be done 5 year the useful life capital goods as prescribed in Rule.
So if you are doing only Exempted supply through the capital goods then the credit is not available. But if you you are doing only Taxable & Exempted supply then credit is available & need to be availed as prescribed in section 16 of CGST Act , because the credit for any supply is available upto September month following end of FY .
Now come to your 2nd leg Query.
If the fixed asset is sold : In term of Section 18(6) R/w Rule 40(2), on supply of capital goods , the registered person shall pay amount Highest of the following : (a) ITC taken on capital goods reduced at the rate of 5 percentage point for every Qtr. (b) Tax on transaction value of capital goods being sold .