Yes, you are right... First use 2000 IGST credit for IGST payable, than remaining 8000 credit you can use 50-50 or in any proportion as per your choice. In your case 50-50 for CGST/,SGST is best otherwise you can use it's 30-70, ,60-40. ect...in any proportion ( there is no restriction)
As per the Provision of Section 49A of the CGST Act 2017 read with Section 49B of the Act, ITC of IGST needs to be fully exhausted first towards payment of Output Tax and the remaining balance will be utilized towards seting off CGST & SGST liability "in any manner / order".
A new Rule 88A of the CGST Rules 2017 was inserted vide Notification No. 16/2019 - Central Tax, dated 29th March 2019, to give effect the manner / order of utilisation of ITC.
So accordingly you have to set off Rs. 2000 Output IGST liability with Rs. 2000 Input IGST credit and the balance of Rs. 8,000 can be used to set-off CGST or SGST output liability in "any manner/order/proportion."